When you're getting started with serious astrology, one of the very basics you need to learn about is the various astrology charts. You use charts in a variety of ways with your interpretations and analysis.
What is a natal chart?
A natal chart (or colloquially, a birth chart) is a snapshot of the exact location in the Zodiac everything was at the moment you were born from the location you were born at. A standard natal chart has the 10 planets, which includes the Sun and Moon as planets (dubbed the luminaries), but excludes the Earth (so it's Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto). Each planet rules something different in your life and personality, and has its own energy.
A standard natal chart also has the 12 houses. The 12 houses also rule different parts of your life and personality, and have their own energy. Each house correlates to a sign and planet. They are:
1st house: Mars and Aries
2nd house: Venus and Taurus
3rd house: Mercury and Gemini
4th house: Moon and Cancer
5th house: Sun and Leo
6th house: Mercury and Virgo
7th house: Venus and Libra
8th house: Pluto and Scorpio
9th house: Jupiter and Sagittarius
10th house: Saturn and Capricorn
11th house: Uranus and Aquarius
12th house: Neptune and Pisces
There are different ways of calculating the houses, and these are called house systems. There's a bunch of them, but the most commonly used (at least in the West) would be Placidus, Koch, Equal, and Whole Sign.
If you use astro.com to create charts, Placidus is their default house system when you generate charts. I usually recommend experimenting with house systems when you get a little further in your studies to see which resonates most with you.
Check out the article on Intro to Astrology Houses to get a rundown of what each house rules.
There are also the angles, which are the Ascendant, Imum Coeli, Descendant, and Midheaven. In Placidus (and Koch), the Ascendant in the 1st house cusp, the Imum Coeli is the 4th house cusp, the Descendant is the 7th house cusp, and the Midheaven is the 10th house cusp. The cusp of a house is the very beginning of that house.
With Equal, the Ascendant is the 1st house cusp, and each subsequent house follows in the same degree and minute of the signs in order (unless it's using the Midheaven instead of the Ascendant, and then it'll have the Midheaven as the 10th house cusp, an each subsequent house following in the same degree and minute in order). With Whole Sign, the Ascendant sign is the sign of the 1st house, and each house goes in order, and all are at 0 degrees.
Every sign in astrology is made up of 30 degrees; each degree is made up of 60 minutes; and each minute is made up of 60 seconds (just like time!). This helps to pinpoint the exact location of planets and other points in a chart.
Some charts will also have other points, like asteroids. On astro.com, their charts have Chiron (the wounded healer) and True Node (a spiritual point of potential).
The natal chart shows who you are. Everything in your natal chart is a map for your personality and life. That's probably the most helpful way of looking at your natal chart - it's the map of you!
This map is outlined by focusing on your natal planets (the what), their sign location (the how), and their house location (the where). Signs on the house cusps show how the energy of that house is expressed in your life. Your natal planets at certain angles to one another can create positive connections between them, or challenges. There's a lot to unpack in a natal chart!
You can also use the natal chart in predictive analysis by tracking the transit (moving) planets (and other bodies) and how they interact with your natal chart. They can move through your natal houses and come to certain angles to your natal planets and have an impact on your life.
A natal chart requires 3 pieces of data:
date of birth
time of birth
place of birth
Date and time of birth determine the exact location of the planets; place of birth comes into play for the houses.
What is a progressed chart?
With a progressed chart, one day is added to your date of birth for every year you've been alive (how old you are) to create a new chart, the progressed chart. This chart is reflective of how you change and grow with age. The natal chart remains a fixed constant, but we do change over time. The progressed chart is where that's shown.
The progressed chart is also used in predictive analysis. It can be used by itself, when your progressed planets and house cusps change signs or come to certain angles to one another. It can also be compared against your natal chart, and you can track the transit planets and how their interact with your progressed chart as well.
What is a return chart?
A return occurs when one of the transit planets returns to the exact location it was at when you were born. A return chart is a chart created for that moment when it happens. Return charts can show how that specific return may impact you. This is a part of predictive analysis. The most commonly used return chart is the solar return chart, which is the return of the transit Sun to your natal Sun location, and this happens once each year around your birthday.
To create a return chart, you need the date and time of the return, and the location you were at when it occurred.
What is an event chart?
An event chart creates a "natal chart" for an event. This may be used to analyze events that have already occurred to see what astrological energy was present and contributed to it, and it can be used to analyze future events you know will happen so you can see the energy around it. To create an event chart, you need the date, time, and location of the event.
What is an horary chart?
An horary chart is used to answer specific questions. The chart is created for the moment the question is asked (location can vary, it may be your location if you're doing it yourself, or the location of the astrologer interpreting it for you if you're having someone else do it). The chart is then analyzed to find an answer to the question.
What is a relocation chart?
A relocation chart is your natal chart, but the place of birth is swapped out and replaced by your current place of residence. Birth time may need to be adjusted if it's in a different time zone (add or subtract whatever the difference is). You're always your natal chart personality-wise (and absorb your progressed chart), but the relocation chart can be used for predictive analysis, tracking transit planet interactions to it.
What is a composite chart?
A composite chart merges the charts of two people and creates a new chart for the relationship itself. It can be analyzed for compatibility, and compared to each person's chart. Transits can also be tracked to it, and it can be progressed. Composite charts are a part of relationship astrology.
Creating a Chart on Astro.com
I usually recommend using astro.com to create your charts - it's free, you don't have to download anything, and it's remarkably robust. If you end up getting serious about this astrology thing and want something fancy, you can opt for astrology software at that point.
Go to astro.com, and click on 'My Astro' in the upper right. Choose to either generate a chart as a guest or to create an account (creating an account allows you to save charts you create). Then you'll be taken to the 'Data Entry' page, where you'll submit your birth data (for a natal chart). Once you submit, you'll be taken to the 'Free Horoscopes' page - click on 'Extended Chart Selection'.
If you want to create a natal chart, that's already selected in the drop down menu, so you can just go right ahead and click to create the chart. If you want to create a progressed chart, you can select progressed chart from the drop down menu (it'll generate a progressed chart for that day). Same with a solar return chart or lunar return chart (return of the Moon) or relocation chart. To create an event or horary chart, when you're in 'My Astro', input the date, time, and location for the event or horary chart instead of your birth details, and then go create the chart as a natal chart.
The Free Astrology Courses page also has a video showing how to create and read charts on astro.com.