Contests are completely separate and different from our regular submission process which is always available on our site. Our regular submission process is not a contest, and MOCs are selected internally by the MOC Nation team. The regular submission process is entered through the Submit page.
Contests, on the other hand, are announced and hosted from time to time on our site. When there is an active contest running on our site, submissions are viewable in a Vote section of the site, and MOCs are competing for most votes and comments, among other things.