Where do I put I am a full time student

That may occur in two different places.  First edit your personal info in the Personal Info / You and your family section. 

Later, in the Federal Taxes / Deductions and Credits / Educational Expenses and Scholarships section, you will be asked your enrollment status as part of the education interview. 

You only need to be half time or more to claim a credit.  Being full time has other implications, mostly whether you can be claimed as a dependent. 

To change your student status, go to the personal info section then select the pencil next to your name.  Walk back through the steps to get to the question asking if you were a student and then select yes that you were a student.