I can't find any HD Apollo Justice or PC Phoenix Wright gifs, so I want to try to make my own instead of relying on others to make it. The problem is, I haven't found a single tutorial on how to make it. Can someone give me the steps you need to make your own gifs from a spritesheet?

For one, there actually is a place where you can access GIFs of these (but it's not complete, unfortunately). https://rippingresource.carrd.co/#
And if you want to learn how to do it yourself so you can help out, join the server on that site.