Cantering??? Need some advice :)?

well obviously you're going to need a good reliable horse. Start her up in 2-point so she can feel the speed then let her come down from the 2-point and sit so she can get the idea of that then go from the sitting trot to canter transition. Once she has gotten the hang of transitions and speed for short distances work on her form and longer distances. You want an enclosed space like an arena if you dont have an arena that would be good try lunging