How do I book a flight for my 12 year old to fly alone

I know that when i flew alone at a you age like that we actually had to call the airlines and have them book the flight; this was about 12 years ago, so i am unsure if things have changed but that's what I would do.

Determine which airline you wish to use first. The term is Unaccompanied Minors. Each airline has their own policies. For instance, SW Airline's website has a Q&A section n Unaccompanied Minors along with their Terms & Conditions, and a telephone # to contact them.

Depends on the airline. Most charge a fee for unaccompanied minors. You can also get a pass to accompany them to the departure gate. Check your airline website.

I would call the airline just to be safe.