How do I connect my second controller to my xbox 360, I want to play halo 3...

[Susan]

...campaign as split screen ? Please help
its wireless

 

[Onion Johnny]

Turn it on by pressing the big X button

Press the sync button on the console, a little white button with three arrows >>>, until the ring of light spins

Press the sync button on the controller until the ring of light spins

Both rings must spin at the same time to connect

 

[Sidekickboy]

is your controller wireless?