Where do participant submit their work? I don't see any form,
It's not mentioned that you have to send your entries in some form. Instead of finding forms, look at this quoted post.
It is too long since we had contests here hence many people would have forget how to submit and for other new people this must be their first contest. Hence, showing them some example will help to understand better.
Here are few links on how an entry was submitted to a signature contest.