Add a game
GameWiki lives of your input, of you going and adding new games. First you need to register (a 5 second affair, no email needed) then you can instantly start. To make life easier, there is a tool called the GameWiki Game Creator. On that page you can simply enter the data for the game and then press the button on the bottom of the page. It creates a link you can follow to a page where you can add the game, as well as the first content for the page. Reading that one page will give you a lot of details right there.
You can also look at an existing page, click edit and see how it is done there. Try to keep it uniform what is already there or discuss changes in the talk pages you can find on any site.
If you have questions about adding games, click on the discussion field above and edit the page to add what is bothering you.