What is numerology?
Numerology is the study of numbers, not in a scientific way, but in a symbolic, mystical way. Numerology sees the soul of numbers.
How to Break Down Numbers
In numerology, you need to break numbers down to a single digit, 1-9. When you add together, say, letters in a name or your birth date, it can total a large number, in the tens, hundreds, or thousands. You'll need to break that down further. Whatever the number comes out to, you take that number and add each single digit in that number. If the resulting number isn't a single digit, you keep doing that until you get a single digit. For example, let's say you're born November 11, 1959. To get your Life Path number, you have to add together your entire birth date. Add together 11 (November is the 11th month), 11, and 1959, totaling 1981. Then you'd add 1+9+8+1= 19. Then you'd add 1+9= 10. Then you'd add 1+0=1, and that's your single digit.
Letters = Numbers
Every letter in the alphabet corresponds to a number. The Pythagorean system is the one most commonly used, which is below. You'll use this to figure out the numbers within your birth name, which are used for some of the core numbers. You can also find the numbers in words themselves, and see what numerology says about those words (Example: The word LOVE is 3+6+4+5=9, showing it's universal; just the vowels show the soul urge, and O+E=6+5=11, showing it inspires).
Your Personal Year
Another important aspect of numerology is using it for predictive purposes. The main number you'll look at in that regard is your Personal Year number. One method to calculate your Personal Year number is to add the Universal Year number (the current year reduced to a single digit; for example, 2015 is 2+0+1+5=8) to your Life Path number, and reduce to a single digit, getting your Personal Year. Another method is to add the Universal Year number to your Sun Number and reduce to a single digit. Try both ways and see which resonates with you.