You click on the Submit link to the left of the Community link. Also you do get points for submitting a game, you get 20 points for each game that you submit.
Like Coolhaha said, but really its not that easy you gotta have consent from the game owner and ArmorGames has to go over it first, then it may be added.
Yes, but the game has to be your own, no stealing games from other sites. And also, this topic has been posted in multiple places, although the first that comes to mind is here.