Halo 3 help?

[tigerboy8900]

I just got the game yesterday. I trying to figure out how to play with other people online. I have everything needed for xbox live (gold membership and internet) so that doesn't matter. What do I click in order to play with other people besides my friend. Btw, my gametag is xavier10469. If you want to, we can talk online. Also, I'm new to this whole halo thing.
Can someone talk to me.

Gametag: xavier10469

 

[DemonSlayer06]

dude halo 3 rocks can not wait till halo 4 comes out pretty soon i hope lol if you have all that stuff then you should be able to play wgainast any body in the whole world to you have your manuel just read it in it will tell you have to inter act with other on halo 3 i even have my sisters playing halo3 in there game tag is jackyl99043 that game rules hell yeah we listen to pantera while playing this game

 

[Soccergirl]

ok u can read the manual and my bro would probly like to talk to u but he dosent want me to give his username out

 

[moose_inks1]

Matchmaking