I was told to start quite low then bring it up like a windscreen wiper for the two handed , what do you recommend i do for the one handed ? Thanks
Well for topspin you have to start low as you said. For me with a one hander, I try and get the racquet head low and use my wrist to generate the topspin.
Bend the wrist down and then flick it up when you are hitting the ball and follow through with your arm.
Its very difficult to explain the motion without a demonstration.