http://www.simviation.com/fsdesign_tute1.htmCheck towards the bottom of the page for several repainting tutorials.
In order to create your own airline - do you have an idea of what you want to do? Have you flown for any VA yourself?
Do you want others to join and be part of your airline?
Why should anyone be part of your airline? What are you offering that's different from the hundreds of existing virtual airlines?
In the grand scheme of things, to create a virtual airline, all you need to do is say "I have a VA." and it's created.
There is no "Central Virtual Airline Regulating Board" with which you have to register.
However, answering for yourself the above questions will go far towards setting the basics for your airline.
How familiar are you with the running of a virtual airline?
How are you going to set up routes?
Will you be a global, regional, charter, cargo, etc. carrier?
My advice, join up with an existing airline, learn the flying and become part of the "operating" team. What will you contribute? You might find yourself opening a niche within the airline, or spawning a new division as you learn...