For "income" on rental house, do I list GROSS payments (monthly rent) rec'd from my tenants? Or do I only list the PROFIT I make monthly (rent - mortgage = profit)?

I am concerned that I am overstating my "income" from rental house.  My tenants pay me $3200 per month, BUT I have a SunTrust mortgage that I pay at around $2900 per month.  So is my "income" from the rental $300 x 12 months = $3600?  Or is my "income" $3200 x 12 months = $38,400?  If the latter is true, then where do my taxes take into account my SunTrust mortgage payments that are "expenses" that allow me to be a landlord and collect rent?