I would like to host online video game tournaments. Can someone help me make this happen?

I would like to start on online tournament business where people pay a membership fee to my website, then they are able to participate in online tournaments and win prizes. I need help making this legal. I am talking about licensing and copyright laws. I need help getting permission to use a certain video game. I have tried many different things but I have no way of doing this. Please, can someone help me?