Yes, you must enter the 1099-SA.
The 1099-SA is a form from the HSA plan administrator which reports the amount of distributions from the HSA, presumably for qualified medical expenses.
To enter the 1099-SA, go to
Federal Taxes->Deductions & Credits->Medical, and click on "HSA MSA Contributions". After you indicate that you (your son) have an HSA, entering the 1099-SA is next.
Be sure that you go all the way through the HSA interview, until you are returned to the Your Tax Breaks screen.
