If you click on the very bottom link in the forum description, which says: "NEW FOR 2014: Log completed assignments using this ENTRY FORM", or "Entry Form" from the list of Prep Rules, it will take you to the submission form. I'd give you a direct link, but since you need to be able to access this link every time you want to log an assignment, finding it on your own NOW will be most beneficial to you.

Choose "NEW USER" (the very last option in the drop down menu, so scroll all the way to the bottom) and you should be able to add yourself.