changing dimension schemes in extrude sketches?

Can someone point me to a good explanation or youtube on how to change dimension schemes in Creo 9?

For example, if it want to locate a crank-pin on the face of a cylindrical model, I would want the dimensions to by the diameter of the pin and the radial distance from the axis of the cylinder, not the dimensions to two planes.  It looks like there is some simple way to step the dimension set through the choices which will work.

I is there a group of training videos here that I can access to learn some of these improvements? If so, where are they?

Yes, I know this is a simple question, but.....