Was this a personal property you sold? That would be reported in the "Sale of Home (Gain or Loss)" section. Or was it business property such as residential rental real estate that you've been reporting on SCH E? That sale would be reported in the Rental & Royalty Income (SCH E) section.
Either way, when you report the sale in TurboTax, you will be asked if this was an installment sale. Say YES, and follow the screens. It can get tricky if it's SCH E property with multiple assets, and for an installment sale you'd probably be better off reporting it in the "Sale of Business Property" section.
The particulars depends on "what" you sold (business or personal) and where you're reporting it in the program.
As a final note that really has nothing to do with taxes, I can't stress enough the importance of keeping all of your paperwork. In my experience with owner financed mortgages (which is extremely limited) the chances of you forclosing in the next 2 years is 80%. In the next 5 years is higher than a 95% probability. Hopefully, you utilized legal counsel for this so that all your bases are covered and all the ducks are in a row for when that time comes.
