My friend has started smoking?

So the guy I like dating one of my so called friends(jess) is now smoking and possibly doing drugs. And at this point I don't care about who the h*ll he's dating, I just want him to be happy and not destroy himself.But Meranda ( who is a bit of a liar told me this so I want to ask him and get him to open up) But would it be better if I told him some of my issues to get him to open up? where/when should I talk to him about this? he goes on th bus after school so no then maybe offer to go to my house or subway(but everyone goes to subway) to privately talk during lunch. tonight is Wednesday, so I could wait until friday, which I could ask and make sure that he is going to youth. Then talk to him. We are kinda friends so. Ya I really don't want him to fall, I want to see the beautiful smile he always has had I don't want it to fade away and die like my uncle(I've seen the long term effects). So If you could please help me that would be great. Thanks so much.Sorry of my horrible spelling too!