HI We just rescued a boxer

Felicia Searcy

We just rescued a boxer pit mix so I am new and want to do the right thing from the start. He is 11 weeks old and is cute now but is already showing some strong behaviors. He barks at me when he wants what I have and back my other boxer up already. He is also chomping a bit with his mouth. Any suggestions on what to do when he barks directly at me and when he snaps?