Where do I add in room and board for college expenses? It's not in the 1098-T.

Room and board are not qualified education expenses but can be paid with funds from a 529 plan. 

You do not enter room and board, in TurboTax, unless you also entered a 1099-Q for a Qualified Tuition Plan (QTP) (ESA or 529) distribution. 

In that case, you must enter the 1099-Q before you enter the 1098-T or any educational expenses (this alerts TT that you qualify for the room & board deduction).  To get the screen to enter Room & Board, answer yes when asked if you have book expenses.