Once you have bought the Name in the Game Tier, you need to activate a forum account if you haven't done so already. Armed with that head here:
Your entry gets sent to us and we read every one and approve them, or reject it and give a reason why. We send you an email so you know when this stage has been completed.
You can submit entries as many times as you like, but each one will require authorisation. If you make a mistake, or change your mind, just resubmit it and it'll make it's way into the next alpha build.
You can check all the current entries here:
To see if you have been authorised, select the "authorised" button and when the entries appear press ctrl+f in your browser and type in your name. It'll take you to your entry. If you can't find yourself, check the unauthorised list and you'll know that we haven't gotten around to you yet.