Press the xbox button in the middle of your remote, then flick the joystick to the left, it should change a menu, then scroll down to redeem code. Enter your code in and press start, then follow the given instructions on the screen.
DUDE CALM DOWN!!!! For a start, im sure ive said this in about 5 other previos posts, WE ARE NOT OFFICIAL 343. We are the community forum, but we can help you and give advise. Next, mind your language please, thanks. Also what actually is your problem? redeem the codes on xbox.com, that might sort it. For lagg i dont know because i keep getting put in games with laggy connections. And betrayals, well people only betray you if you did something to them (so watch you language online, dont kill people for weapons(unless hes a bad-guy) and just ignore people that steal vehicles.).
And because its their first game you should EXPECT PROBLEMS it takes time and experiance to make a perfect game. Furthermore DON'T DISRESPECT BUNGIE! Without them there would be no halo, they did great jobs making the first 5 halo games (Halo CE, Halo 2, Halo 3, Halo 3 ODST, Halo Reach)
They are quite frequently, all you can do is play offline until thyey come back up.
Yours,