[Alan Anderson]

Use the Rectangular Target - 2013 vision example project. It contains step-by-step directions for adding it to an existing robot project. When you set it up appropriately, it tells you where the center of the target is, right or left of and above or below the center of the video image.

Then you can use the left-right information to decide how much to rotate the robot, and the up-down information to compute how far away the target is.