How am I going to convience my mum to let me go to dragon con?

I am going to be 16 by the time dragon con comes around. My mum is protective ,because of my previous rebellion, but i've calmed down. Lately I've been good and staying out of trouble. A couple of my friends are going to attend dragon con along with two parents and I want to go. Also if she ends up saying yes how much are the tickets, where can I get them, and what do they do there?