What do I need to travel by plane?

I would like to travel from Montreal,Canada to Las Vegas, US...the problem is I've never travelled by plane by myself and I was wondering everything I need, I have the money and im 20, I have a passport and money...Where do I need to go to buy the ticket, I would like to travel the 25th february(at night, and I would like to come back for march 1st,..I want to keep this from my parents because they might say no, so Im gonna try to sneak out with a cab , however as you may see im pretty clueless, was wondering also if I need a VISA or somethin, I only have cash, also when I get there is it hard to find a motel or hotel, I dont have my license yet so im gonna have to take a cab