Go to VATSIM -> Community -> Virtual Airlines

From there you will see the requirements to become a VATSIM Partner. I would advise you to join a current VA and learn how to effectively operate an organization from an established source. Then, if you think you can handle it you can branch out and create your own. It is a very time consuming task, and it is going to cost you a fair amount of money to host a site and other resources for the VA.

Many VA's fail because they are simply trying to replicate what is already out there. I don't want to squash your plans, but I also don't want to see you put a ton of work into something that won't succeed. I'd be happy to exchange email with you privately to discuss how you can establish a credible VA, and once this happens I can guarantee you contact with Kyle Ramsey, VATSIM VP Virtual Airlines.