To do an upright flat spin, put the plane in a climb with the throttle at idle. When the plane stalls, input full left rudder, full left aileron and full up elevator. Once the plane goes into a spin, neutralize the ailerons. Some planes spin flatter with opposite aileron and some throttle so you have to experiment with your particular plane. To spin the other direction, do the inputs to the right. An aft CG helps and you must also have enough throw in your rudder to enter a spin.

Important: Most planes recover by neutralizing the inputs, adding throttle and pushing the nose down to gain airspeed. Some planes need opposite rudder to stop the spin. If your plane does not recover within a few rotations, apply opposite rudder. You would be smart to let someone experienced spin your plane the first time so you can know what to expect in recovery.