how do i put oil in my hayter 2013 model ?

where do I put the oil I have a 2013 hayter which I have taken apart and cleaned amd have drained the oil and it al runs but I cant find where I put the oil as theres a apart wich has "fill drain " so do I take that off and put that in there or put it straight into the engine by taking of the exhaust and put oil through there as there is no oil compartment to messure how much is in there ?