MINECRAFT MODS/SEEDS/WHATEVER?

(Xbox 360) I've seen people do it before, in super flat, creative. They make big blocks into smaller blocks. And every YouTube video and endless google search nothin shows up. Only PC versions, and their in survival. I know how to do it in survival, but it's not the same on the creative mode. If any one can help a fellow minecrafter' out that'd be great!