How to change my iMessage information on the iPhone 5 with ios7?

My brother and i are sharing the same account by accident so whenever we message each other it just goes back to ourselves. I don't know how to change it, i've tried everything. Its really annoying when I really need to text something to him!

You go to settings>itunes/applestore>then tap on your name and you will get the option to sign out (which signs out on everything that uses an apple id) then enter your new id

Sign out of imessage and sign in with your own apple id. You can set up send and receive in there. Sign out of facetime and icloud too snd put in your own apple id. You can still remain signed into the itunes store and both use that account.