It's very very easy. All you do is take your temperature at the same time every morning with a basal body thermometer (Which you can get at drugstores). Regular ones will not work as they are not sensitive enough. (trust me I've done trials lol, and they need to read 97.77) You simply add the temperature into
www.fertilityfriend.com
From the first day of your period to ovulation, estrogen is the dominant hormone, which is the "cool" one. From the day after ovulation until your next period, progesterone takes over, which is the "warm" one. The day after you ovulate, you get a temp rise of at least .4 degrees, which will stay up until AF or will drop a few days before hand. The days between ovulation and your next period is called your luteal phase (LP). This never changes, but only varies a day or two.
With FF, you get crosshairs after 3 raised temperatures confirming ovulation. You can look at my charts for examples. You'll notice there is a definite difference in temperatures, that's how you can tell you ovulated.
Charting is super easy. It is a lot more stressful NOT knowing what's going on and if/when you're ovulating instead of not knowing. A lot of women have shorter LPs and ovulate on different days each cycle and they BD on the wrong days.. it's good to know this kind of stuff when TTC. Charting has helped me TONS, especially with my long cycles. Hope I explained it for you xx