With an adult boa that's a known quantity it's pretty straightforward: provide a good reptile enclosure or even a large tub, dial in the heat and humidity, give him a few weeks to settle in, and enjoy your new pet. I would ask whoever has him now for any other info, such as is he hook trained, what size feeder is he on and how often is he getting fed, etc.
Obviously you'll need to quarantine him, and I would suggest six months rather than the standard three months with his background.