To give you the basics then it goes like this.
You temp every morning before getting out of bed and before starting to move around. You enter the temp to your chart daily. Ofcourse temps are going to go up and down most days but you will still clearly see that when you ovulate then the your temperature is on average higher than it was before O. That way you can pinpoint your ovulation. You can also enter results of OPK-tests as well as all sorts of other fertilitysigns. What kind of CM you are having, how your cervix feels etc.