Question (Maybe TMI)

I'm curious to know what the whole fertile days means. Is it basically saying to have as much intercourse as possible so that the day you ovulate you have a higher chance of becoming pregnant? Also how do you know if you are actually ovulating? This is all son confusing and frustrating. I always assumed you just find your partner and have your baby. Boy was I wrong. Its been two and a half years of hoping and trying already. Also has anyone tried the preseed? At what stage do you use it?