All you need to do is to press A and update your console. For online play, regular updates are mandatory. Also, you'll need a Live Gold card to play online, which is around 5K a year. It can be bought from PG Store. But for the first three profiles you make on XBL, you get 1 month Gold free on every profile. So just update your console, its confirmed that its hacked with the latest LT+ because it can run AC:B and it is perfectly safe to go online. But do confirm from where you bought the console that how it is hacked, LT+ (totally safe on Live) or softmod (not safe at all on Live).