You should be more careful about how you use language.
I don't know how to use iPhones.
I’m going to train my dog how to use a hammer and bring him to work with me.
You've seen the word 使う hopefully by now. If you have, you know it means "to use." So, the way to use something is the way of using (aka how to use). This will be a word you see when you're looking at directions for how to use something.
The readings come from the vocab words 使う and 方. So long as you're okay with those you can apply that knowledge over here.