Turbotax is not allowing me to tell them my Roth IRA distibution was used for qualified higher education expenses. Where do I enter this info?

After entering Form 1099-R continue through the interview and, if this was an early distribution, the program will ask about exceptions to the penalty tax. 

If this was not an early distribution, there will be no penalty tax. 

There is no exception for the distribution to not be (partially, on earnings only) taxable income. 

If this does not answer your concern, please provide the code in Box 7 and tell us if you are being charge the 10% penalty.