Having done this many times,
You send the seller a copy of your receiving dealers FFL by fax, email or snail mail along with payment. He ships the gun to your dealer. You fill out the 4473 and any other forms your state may require as well as the NICS check and pay your dealer his transfer fee (usually around $25). Should not be any sales tax as it's an out of state purchase, but, some states are starting to charge it anyway.
Waiting periods depend on individual state laws.