MissHarris, You either use an Ovulation Predictor Kit (like a pregnancy test but for ovulation) or you learn to read your body and emotions.
When you ovulate, your cervical mucus change to wet, clear and super stretchy (like raw egg white). Your cervix are high, open and soft. You might feel more healthy and horny and your skin will clear and smooth and your hair shiny.
You can also monitor your basal body temperature (BBT).
You can look at a site like FertilityFriend (dot com). They have plenty of free training that will teach you how to figure it out. Here is a link to a fertilityfriend thread in the Pregnancy forums:
http://ehealthforum.com/health/topic114094
.html
Best of luck TTC!!