You really don't need to enter the 1099-S anywhere. But the fact you got one, means the IRS is expecting you to report the sale, weather you need to report it or not.
The 1099-S shows gross proceeds paid to you at the closing. The total of those gross proceeds may or may not be taxable. it also may be less than what your sales price was to. Typically, the 1099-S will show less than your sales price, since the amount of the sales price used to pay off any existing mortgage is not generally included on the 1099-S.
