I've recently been working on a game. I know how to make a title, but have no idea how to make the description on it.

@description (description)

Is it as simple as that, or is it some other way?

If you mean after you check it in, there is a description field for that (where you can type it in. You'll find it under "Edit this Listing" on your game's page. Otherwise, I'm not sure how to get a description into a game and how that would even look...