Interest on a private loan for personal expenses is not deductible, so it will not go anywhere on your return. Only interest for items such as mortgages, business/investment expenses, or student loans are deductible
See excerpt and link below for further information:
Types of interest not deductible include personal interest, such as:
- Interest paid on a loan to purchase a car for personal use.
- Credit card and installment interest incurred for personal expenses.
- Points (if you're a seller), service charges, credit investigation fees, and interest relating to tax-exempt income, such as interest to purchase or carry tax-exempt securities
https://www.irs.gov/taxtopics/tc505.html
