Which state do you live in?
Were you ever a felon or charged with a crime that falls under the Lautenberg Act?
Are you addicted to any controlled substances?
Do you have a clean criminal background?
The procedure in most "free" states is that you go to a licensed firearms dealer, pick out the gun you want, fill out the ATF form 4473, submit your state-issued photo ID and wait while they perform a telephone check to NICS to verify your information on the 4473 form.
Then (assuming your NICS check is PROCEED) you give your money to the cashier and go home with your gun.
UNLESS you live in a state that requires mandatory waiting periods, registration, "safety inspections", etc. in which case those laws are what is governing the transaction.
Or, in a really free state, you meet somebody who has a gun they want to sell, and if you both live in the same state and you both mutually agree that to the best of both of your knowledge, each of you are fine upstanding citizens, and you give them money and they give you your new gun.
Just like what you would do if someone had a lawnmower, a couch, or a 36-volume set of Encyclopedia Brittanica they no longer wanted.
You are (still) able to freely do with your property as you see fit.