You may want to read the book "Taking Charge of Your Fertility". Very informative. If you are TTC I really don't think you necessarily need to read the book, just go to a site like
FertilityFriend.com and take your temp every day and slowly find your way and learn about fertility signs like cervical mucus and position, saliva scopes..... Each fertility sign you track past your temperature will make your chart that much more accurate. If you run into trouble after a couple months and feel you need more details, reading the book will really help.
Now, if you want to use NFP as a form of birth control, you need a whole lot more information IMO so read the book

In fact I personally only recommend NFP to people who have been charting a while when TTC or if they chart for several months while using something like condoms (also, your chart and fertility SxS can be a little different while on chemical birth control, so even charting for a couple months while on the pill won't give you a good representation of a normal cycle for you. You really need a few charts where you can understand your natural pattern where you feel you can predict ovulation) You really need to get the hang of things before depending on it to help you avoid pregnancy.
If you want some tips on how to get started, let me know
