I can't figure out how classmates can add photos to the photo gallery - not just their own profile....

I'm assuming you figured it out on your own, as you've already done everything perfectly. 2 of your 3 galleries are set to allow Classmates to upload photos. Within each Community Photo Gallery Classmates can upload and maintain their own little gallery. All they need to do is click the "Create Your Own Photo Gallery Here" button and then follow the directions on screen.

Note, when you click your "Photos - Then & Now" link, default instructions are on that page that instructs Classmates how to upload photos to your Community Galleries. While the instructions work well, they're not set in stone. If you want to change them or add to them at all, just click your Gallery Creator link and then click the Edit button next to the gallery navigational link. You can change those instructions to anything you please.

I did figure it out - thanks for getting back to me!