Enter it in the VEHICLE section of the Sch C input entry ...
You are asking from TT Live, for which you pay extra. Please contact a rep for one on one directions: https://ttlc.intuit.com/questions/4124827-how-do-i-connect-with-a-tax-expert-in-turbotax-live
If "we" are self-employed then "we" can't be filing a SCH C (with one exception). So business vehicle use may not be claimed on your personal 1040 anywhere, depending on the "type" of business "we" have.
