Classmates are sending me photos that they want me to paste in our Photo Gallery. When I do it, my name comes up as the one who uploaded. Is there some way that I can change my name to the classmate who sent me the photos for posting?

You could ask for their login and password and log in as them and post as them. Although that would really defeat the whole purpose of having a Community Photo Gallery. As the effort involved in emailing you a photo attachment is no more significant than simply posting the photo to the gallery themselves, why not have them add the photo directly to the community gallery? When they do that, the photo of course will be credited to their name, not yours.