hi and welcome.
Check out the links and threads found here
Fertility Charting School - JustMommies Message Boards
You can use taking charge of you fertility (I actually read that book to learn about charting). Several people get an account on fertilityfriend.com. Like the PP said take your temperature every day at the same time and record it. Watch your cervial fluid, it should transition from dry crumbly, to sticky, to creamy, to watery or eggwhite and back again. Any cervical fluid is considered fertile however slippery/watery fluid is best.
Most software looks for a clear thermal shift with 3 days of higher temps and then the presence and disappearance of fertile fluid