Near the top of the page you should see some buttons titled "browse", "shop", "submit" and so on (they are located just below where it tells you if you have any new messages). Click on the "submit" button, this will take you to a new page where you have the option of what type of thing you would like to submit, click ont eh "deviation" option then scroll down a little and click continue. From here you just have to continue clicking the categories that suit the picture that you want to upload.
I hope that helps you, and I hope it wasn't too confusing.