Help with tracking

I am rather new to Principia, and I am trying to make a simple robot that could be produced by the multi-select. The tricky bit is the fact that I want the robot to use an object tracker to follow and fire in the general direction of whatever the object tracker is tracking. The robot is not going to fly or go over any tricky terrain, so I just need a circuit to adjust the wheel direction and rotate a servo for a weapon mount. Can someone help me out with this?