How Do You Set Up A Two Player Online With Call Of Duty 2 Using The Xbox 360 Under The Same Console?

I play call of duty 3 online with two players under the same console. I recently bought call of duty 2. I know you can do the same thing but I dont know how to. Where do u have to go under the Multiplayer screen? How do u start a two player online match on Call of duty 2? Thanks