how serious is a first offense, trying to buy xanax

My son attempted to buy xanax from an undercover. I found this out because we couldn't find him. After calling my local precinct and hospitals the precinct told me to call brooklyn central booking and I found out he had been arrested for attempting to buy xanax. actually I found that out from my neighbor who happens to be a deputy chief and he called the central booking. Told me my son would be out in three hours and would get a court date. How serious is this and what should we do? I don't have many of the details. At first the central booking told me to call tomorrow morning and they wouldn't give me details other than attempting to buy drugs. It was my neighbor who got the other details and told me my son would be out and home in three hours.