well i cant tell you this its alittle more than cg..its difficult to explain. there are many ways to enter but the easiest i think is this... fly at about 45 degrees(up) let off the throttle and hold off till the plane begins to stall. ease it into the stall as soon as it stalls bang the rudder to the right and the elev.full up
(down stick.)slowly hold imputs and feed throttle.if you time this right it will develop a flat spin pretty quik.the stall point ithe important part if not acheived right the spin will never develope into a "flat" spin.it will be more like a nife spin instead.you can also invert the spin by tring this
pull vertical at half throttle chop throttle(at high enough altitude)hold perfect vertical till plane stalls just before the stall point push back on the stick to push the plane inverted.not to much just enough to be invert position then bang left rudder and hard up elev.now the hard part its a feel you must see the plane and imput the controlls at the right time to work. go out and practice with these and let us know if it helps... the dave patric areobtics book is a real good way to start.but mainly its watching the plane closely and useing your sticks to minipulate the plane into the desired position... like i said hard to explain hopw