I joined Fertilityfriend.com on a free months trial, I found it really helpful for charting and they have a Q & A section to help you too. I bought a thermometer from boots (they do a pack with a BBT (Basal body thermometer) and a chart which I didn't use. It was a tenner I think. But you can get them off Amazon etc but it needs to be to .2 decimal places to be exact. Then you just record your temperature at the same time every morning (or as near to as possible) and put it on your chart. You start from CD1 and you can also chart your cervical mucus and other symptoms as well to build up a better picture right through your cycle. Basically before you ov, your temps should be lower, once you have ov'd they will rise, and stay that way until your af is due, when they will decrease again. Its handy if you are unsure if/when you ov and also to watch out for a temp dip after ov etc for implantation or increased temps for pregnancy. I've added a link to my chart so you can see.
[url=https://www.fertilityfriend.com/home/348753]My Ovulation Chart[/URL]