I fielded a question earlier today about how this whole seed thing works. During the course of that conversation, I attempted to pull up an X-box Minecraft screenshot of the "create game" menu screen and was told by Google that no such screenshot exists.
Well, now it does.
Behold, I have taken a screenshot and posted it here in case anyone else is interested in playing with seeds but isn't aware of exactly where to put the seed in order to get the level to generate. After you select "create game" from the start menu, you'll see this screen prompting you to name your save game, select options for connections to friends and X-Box live, and the seed name. If you leave it blank, the game will simply choose a random number to use as a seed.
Of course, that can be fun, too. But then what would you need me for?