Hi Jim,
Panning your camera while using low shutter speeds can create some wonderful effects, but it does require some practice to perfect.
The slower the shutter speed that you use, the more blurred the background is likely to be. The real challenge is in making sure that you track your subject accurately so that it stays sharp while everything else becomes a motion blur.
In this photograph you have used a shutter speed of 1/500th of a second but I notice that your aperture was set at f11 and your ISO at 500.
To get a slower shutter speed the first thing that I would do is adjust the ISO down two stops, from 500 ISO down to 100 ISO; as the ISO is decreased you require more light on the sensor to gain achieve the same exposure. To do this you can increase the exposure duration two stops by slowing the shutter from 1/500th down to 1/125th of a second.
If you want to slow down the shutter speed even more then your next option is to close down the aperture; at f16 your shutter speed will drop to 1/60th of a second and at f22 the shutter speed becomes 1/30th of a second. By now you should really start noticing some blur in the background.
If you want a slow the shutter speed down even more then a useful technique is to put on a polarising filter. This will take another two stops out of your exposure so that in this instance you could use a shutter speed of 1/8 of a second.
By the time start getting to the lower shutter speeds it can be useful to use either a monopod or a tripod to hold the camera steady; carrying a tripod to the track might not seem like a fun idea at the time but it really will help you perfect this technique and achieve some amazing photos. I hope you give it a go.
Cheers, Anthony.