There are many fantastic articles in the HEALTH PAGES (located at top, right corner under the search engine).
Basically you'll need to know when you ovulate. There is only a 48 hour of opportunity to become pregnant in a cycle. You also need to know if you are regular/irregular, how long your cycle lasts (average is 28 days), and some ways to chart your fertility.
Ready?
Have you tried an ovulation prediction kit?