How do you enter an online match on Halo 3?

[Chae]

I haven't played it on my Xbox 360 in over a year and I cant remember how to get into an online match. I've gone to matchmaking and chose team doubles and stuff but it just goes back to the matchmaking screen and just sits there.

 

[natisha2000]

you plug i the internet to the xbox. and you go to the main menu. I forgot what Button too press but you press one of them and play online! i am sorry if this doesn't help because i don't really play halo3.