All booked and paid :D (onur air)

Finally booked it .. Staying in the bahar for 2 weeks on july 10th. My 24th birthday on july 20th so really looking forward to that 
Just a lil quick question usually when we fly i get legroom seats but i don't know how i go about it with onur air? do i ring someone and ask and pay or just wait until i am at the airport

Just a lil quick question usually when we fly i get legroom seats but i don't know how i go about it with onur air? do i ring someone and ask and pay or just wait until i am at the airport