First, I want to welcome you to MobileRead and let you know that people here are listening.
There should be a copy of the User's Manual in the Library on your PE. That might provide the answers you seek. I can try to put pictures in the Gallery on my PE and then tell you what I did. It is probably fairly simple, like using the file manager to put them in the right folder, but I download books and documents a lot more than I do pictures and music, so I can't tell you off-hand.
If you don't find the answer on your own or get a better one from another forum member, I will experiment and let you know.