How do pay turbo tak if your not paying with your refund

You pay the TurboTax account fees with a credit or debit card.  In Step 1 of the File section selection the option shown "Pay with credit card"

If you don't have a credit/debit card, you can buy a prepaid debit card at many stores for a few  bucks.  Be sure it has one of these logos:  Visa, Mastercard, American Express, Discover.

Are you still in the original filing process?     Or did you already file and chose to pay out of the Federal refund, and now the IRS has denied or reduced your refund?

If you originally filed and elected to have your TurboTax fees deducted from your Federal Refund, you can pay your fees at the link below if there's been a delay in receiving your Federal refund.  

https://payments.turbotax.intuit.com/