How do we report land we sold at a significant loss and are doing owner financing. How do I report this? Is the interest payment reportable as income?

We purchased the land 3 years ago. Our cost basis is $77,908.  We sold it this summer for $68,500 and are doing owner financing.

The contract is for 15 years. We got a statement from the mortgage company handling the payments for us, but not a formal tax reporting form.

How do I report the sale and the interest?  I tried to enter as an installment contract, but TurboTax said it didn't qualify, to report it another way.  Help