Here are some of the things you can do here:
1. Post an original.
If you have an original, unaltered photograph that you think would make for good photoshop material, post it here.
2. Post your own edit.
You may reply to the posting of an original with your photoshopped version.
3. Post some classic edits.
To post anything is not a difficult task. If you can put a file on the World Wide Web, you can post. There are even free picture hosting websites. I don't really know what their URLs are, but perhaps someone else does, and will reply.
Once you upload your pic to a server, simply include it in your post via the "Img" button found in the button bar. Press "Img", type the URL to your picture, and press "Img" again. Sumbit your post when ready.
Remember, if you need to go back and make a chage, or you screwed something up, you can always edit any post you've made.
Have fun!
Ian