where do I deduct education expenses (tuition,room, board, etc.) paid with student loan?

In TurboTax (TT), enter at:

Federal Taxes Tab (Personal for H&B version)

Deductions & Credits

-Scroll down to:

--Education

  --Education Expenses and Scholarships (1098-T)

Note that you will just enter the expenses paid. You do not designate that the expenses were paid with loans. That's not relevant, for tax purposes*

You will also not enter room,  board and/or housing. Those are not qualified educational expenses for a tuition credit or for scholarships to be tax free. The fact that you paid housing with student loans is not entered in TT. 

Room and board (R&B) are qualified expenses for a 529 Plan or ESA distribution.  But to get the screen to enter R&B, you must first tell TurboTax that you had a 529/ESA distribution by  entering your form 1099-Q. Form 1099-Q must be entered before the 1098-T is entered. 

*Except to claim the student loan interest deduction, which is entered separately.

In TurboTax (TT), enter at:

Federal Taxes Tab (Personal for H&B version)

Deductions & Credits

-Scroll down to:

--Education

  --Student loan interest deduction