Blowjobs... Help.

Ok so I'm 16 and I've never given a blowjob before. And I fee like the time is going to come when I'm going to, but I just don't know how. And I'm really scared. So questions is. 1. How exactly is it done? 2. How can I be less nervous and scared about it? 3. When do you guys think it's a good time, either a relationship or a hookup?