I would ask of you to be more specific, but since its not possible to change your answer, I'll say both.
To get Forge maps, make an account at http://www.bungie.net/ (I did not need to copy and paste :-P) and download directly to your XBox360, then start a local game and it should say Download Complete.
To get map packs, go to the market place, look for the tab that says "Map Packs" and find the Halo 3 Map Pack you want, then it should download, and then you'll have the maps in Halo 3.
play sonic in halo just download and the maps change
When on Halo 3 in Pre Game lobby you press start and chose Xbox Marketplace. From there you can download the maps and other Halo 3 content.
you cant >:(
yes and no. You can play all the maps in the halo 3, but you have to download the rest.
If you have xbox live you can.
You have to have Xbox live, and you download the maps.
How else would you get them.
Yes you can
all of them i believe
no, you have to download the rest
What you have to do is for the Xbox 360 you have to connect to Xbox Live then you have to get Microsoft points and download the maps but most of the maps are free.
First, You go to the menu then find file browser. you can search maps from there.Second, there is no second