The most common reason you receive an Upload Failed message is because the photo you're trying to upload is too large. This is not primarily a photo sharing site because we don't have a lot of good photo manipulation tools or massive amounts of user storage for these files (which can be quite large when you times it by 100,000 members).
Shrink the size of your photo to the dimensions or file size the system tells you is the maximum before trying to upload it here. If you don't do this, you will receive the Upload Failed error.
If you need more flexibility for photo sharing larger photos or don't have the ability to shrink images, check out any of the free photo sharing sites online, like flickr.com or Google's Picasa:
http://picasaweb.google.com/home
DocJohn