I'm having some trouble with my Xbox, I don't know how to play 2 players on Xbox. I haven't been able to play it 2 players ever, so this isn't the first time this is happening. How do I play with another player?
If you mean split screen, if you have wired controllers, make sure they're both plugged in and go to play Minecraft like you normally would and join the world you want to play in. Once you're in the world you want to play in, turn on the second controller, once the controller is on, and synced, you should see something appear on your screen saying something a bit like: "Press start to add another player" I can't remember exactly what it says but it is something along those lines. That's how you can get two players playing together with split screen.
To play with 2 people with Xbox live, when you're about to load your world make sure you have 'Online game' selected, have 'friends of friends' selected if your friend is going to invite something who isn't on your friends list. Lastly, if you have 'Invite only' selected then you will need to go onto their Xbox live gamer tag and invite them to the game. If you don't have 'Invite only' selected then they should be able to just join.
Hope this has helped.
EDIT: I have just seen the post above mine. I'm not sure if using HDMI does make any difference at all, but just to add I do use HD.