I owe money on my taxes, where do I go to set up a payment plan?

In the File section of the program when you have federal taxes owed, on Step 2 you have the option to request an installment plan from the IRS.

IRS website to apply for an online payment plan - https://www.irs.gov/payments/online-payment-agreement-application

The fee for a payment plan is lower if you apply directly on the IRS web site instead of through TurboTax. When you file your tax return, select the option to pay by check. Then instead of sending a check, go to the link that DoninGA gave you for the IRS web site.