I want to keep him away from smoking because his dad smoke and he is so beautiful. I don't want him to get ugly and lose his pretty voice. P.S. he is an at risk student and I want to help hk but I don't know how and I'm only 13 year old.

You can be an example, and you can let him know how wonderful he is, and hope that is enough. Positive reinforcement.
You can say let's go to the movies and hope that means he won't be able to afford cigarettes. Positive distraction.
You can wave the air and say oops got to leave, if he smokes, without getting angry.

In short, you can make people feel good about themselves for behavior you do like, you can walk away if you don't like it, and you shouldn't put them down.
And you can't count on changing anyone, ever.

You could always tell his parents or yours, his health and well being is their responsibility..

You can always tell him that its bad for his health and you don't want him to smoke around you, but whether you have any influence over him stopping, well I don't know either of you so its hard to say.

Good Advice! (I hit the "YES" button but nothing happened).