1. On the Navbar at the top of the page, click "Galleries"
2. On the page that loads up, above the search box in another bar, you'll see Home · Search · Profile · Upload Photos... Obviously, click upload photos.
3. First up, select which gallery you want your images to appear in. Of course, some galleries have restrictions on them, so choose the appropriate one. I should also note that if you upload to a gallery with restrictions, the images will not appear in the Recent Photos box in the "Galleries" link. (At least this is case for the VIP gallery, not sure about the rest)
4. Browse for the photos on your computer. Enter a title for them, a caption and keywords if you want.
5. Double check the "Extra Options" box at the bottom to change any settings you want.
6. All done! Click "Upload/Submit".
If it doesn't work after this, then there's definitely a problem.