Follow the steps below to enter your 1099-S

1. Sign-in to TurboTax Online and continue to your tax return or Open your return in CD/Desktop version
2. Type “1099S” in the Search/Find Box
3. Click “jump to 1099s. sale of property other than main home”
4. Click Yes to "Did You Sell any Investments in 2015?"
5. Click “No” to “Did you get a 1099-B or brokerage statement for these sales?”
6. ‘Choose the type of investment’ you sold 
7. Follow the screens to enter information about the sale.

For more information, see below:
https://ttlc.intuit.com/replies/3302480