At the top of the response box you type in, you see a bit to the right of Font and Size a smiley face. Right of that is a globe with a grey infinity-looking thing. That inserts links for us to click on. Right of that unlinks things, and right of that is a square with a tree in it.
Click the square with a tree.
Your screen turns grey, and then give it several seconds till it gives you a Select Files option, or go to Insert URL if you have its web-link to paste in.
Select from your computer.
Then click Upload Files and wait a moment.
If that does not work, you either have a memory-space issue as on some forums you cannot upload unlimited photos; or, it's not a .png or .jpg file which can sometimes be converted by resaving it as a .jpg file.
If issues still persist, email me them at MalemuteKid1@gmail.com and I'll work it from there. Be sure to put your name as ajohn in the first sentence.
Oh, ignore the attached thumbnail photo. I had to walk myself through the steps to tell you them, and I cannot delete the photo.