How do I figure out the fat percent of myself?
You seem a bit young to be worrying about such things, I can't see you needing to know it in any detail. It can't be worked out with an equation, although there are some, which give inaccurate results (check wiki). Other way is to use a machine (looks like big scales), sometimes found in chemists, it just runs a little current though you and gives you an okish answer.
Here ya go, You can calculate it here: