In the meantime, probably what's happening is that you're browsing for a photo and hitting the "Finished" button immediately. Seems harmless enough, but the way the thing is designed to behave, it will immediately start uploading the photo as soon as you browse for it. You should see a little progress bar show up at the bottom of the screen, and the filename box should clear itself out.
You can actually just keep browsing for and selecting photos as fast as your mouse will carry you, leaving that "Finished" button alone until you have your whole stack of photos posted.
Again, nobody ever figures this out the first time! I'll try to make it a bit more apparent what's going on for people who didn't write the thing.
Anyway, welcome aboard. Hope you stick around!
Jason