I also recommend TCOYF -- it really explains it all well. If you're charting online, like on Fertility Friend, you will get an ovulation date/crosshairs after three days of a temperature increase/shift. So, you can't pinpoint ovulation until after it has happened, though after you do it for a few months, you can get a good idea of when you generally ovulate. That's why monitoring CM or using OPKs (or both) work well in conjunction with temping.
I just started temping again this month -- I haven't done it in 2+ years, so I'm trying to get the swing of it again. Good luck with TTC!