you don't, 343 took out custom games kept forge and changed matchmaking to "war games" still the game has rocketed off the charts, also before you even get to play war games or forge you have to have disc 2 downloaded on your Xbox 360 or you have to download it from the marketplace.
Refering to halo 3 and halo reach their is a custom forge game mode, here you can build and shape your very own map creations for both custom and recreational use.
Halo 2 has the gravity rifle in it but i (think) you have to have the custom edition to get the gravity rifle.....
Halo Custom Edition.
On the custom games menu, highlight the game type and press X to edit You can customize all game type
It depends on which game. These are the ones I know so far can be Cheated on- Halo: Reach Halo: 3 Halo Combat Evolved Halo: Custom Edition Halo: 2 Halo 3: Odst
All you have to do is forge it.
at the custom game lobby press X and it should be there
There is no Halo 3 mod for Halo Trial. Halo Trial is one of the hardest versions of Halo to mod. There are however, custom maps for Halo Custom Edition. To get Halo Custom Edition, you need to have Halo: Combat Evolved installed on your PC, you also need your CD key. You can download Halo: Custom Edition free.
To download Halo 3 Forger maps and custom game types, now that 343 Industries has taken over, you have to go through the sandbox.
It is not in halo combat evolved proper, but you can probably get mods with a gravity hammer in it for halo custom edition. It is in halo 2 used by Tartarus but you cannot wield it. In halo 3 you can wield it i multiplayer and campaign. I have no idea about halo odst but it was not in the list of weapons not in odst so I imagine it is in there.
There are 2 disks that come with the game: The 1st has Campaign and Firefight, which is new. The 2nd has the Custom games, with 3 new maps, and a bunch of others that you had to buy off live for Halo 3.
use the forge feature in any game after halo 3. In Halo CE, there is no way to do it.