ok in short:
-write a business plan
-show your business plan to the investors (only in case you dont have the money on your own
-contact the civil aviation authorities, they will tell you what it needs to run an airline
-if you can fulfill all requirements then they will give you the license
Notice that you need enough cash to start an airline (for instance the authorities require you to have enough money to pay the staff for a few months).
It might be better to start with just selling tickets, outsource the flying part to a company that already has a license. They will fly for you while you can concentrate on marketing your flights. Once you are in the business you can work on your own license.
I have an example of an ACMI (aircraft, maintenance and insurance) contract here. I can make a copy and send it to you if you are interested.