THEORY
While it is not essential to understand the theory of riding a motorcycle and sidecar it certainly helps, so here goes. The first thing to understand is that the motorbike with the sidecar will feel nothing like the motorbike without the sidecar. Riding a sidecar combination has nothing at all to do with riding a motorcycle, or driving a car, or trike, or any other vehicle you may have experienced.
A sidecar combination is not symmetric so turning left is not the same as turning right. The most basic part of riding is to understand what should and should not happen BEFORE you try and ride it. When you accelerate all the power is delivered through the rear wheel which is on the right of the vehicle so the vehicle will be getting pushed forward and to the left. When you close the throttle on the bike, only the bike will slow down so the vehicle will be pushed to the right. The trick to riding one is to use this left and right push to help you. So on left hand corners go in very slowly, turn the bars to the left and accelerate slightly to drive the bike round the sidecar. On right hand corners go in slightly faster then seems natural, turn the bars to the right and roll the throttle off slightly allowing the sidecar to swing round the outside of the bike. All combinations shake the bars a little at low speeds, be prepared for it but don't be scared of it.