You need to make it your avatar, I am assuming this is what you mean. Even if it isn't, you still have to make sure it is sized correctly and/or the right format. "Note: The maximum size of your custom image is 100 by 100 pixels or 25.4 KB (whichever is smaller)."
You did successfully upload a profile pic. If you want an avatar pic (that shows up on your posts), that is a separate thing. Simply follow the instructions. Reply if you still have trouble