There is no websites except this one.
The rules for this one are simple.
Read the FAQS, they will help you.
Make an appointment with a local rep in your area.
Bring ID with you. Show said ID to said rep.
Rep will provide the Admins with your DOB.
Admins will grant you access to the classified ads where you can get guns.
There are a ton of reasons for this process. If it's too much time for you then Airsoft is not really for you. Perhaps get a pellet rifle.