Hi!
Welcome aboard. You'll find tons of information here as you search around. Also, be sure to check out the FAQs off of the main site.
http://www.contour.org/FAQ/As to your problem, you're right to think there is something wrong with your VSS as your code of P0500 indicates a
Vehicle Speed Sensor fault. In the future, you can find other codes within the FAQs
http://www.contour.org/FAQ/FAQ.php?s=probs&displayid=10Finally, I would be concerned about your tranmission light blinking. This is indicating a transmission fault, and is seperate (although the problem could be related) to your CEL (Check Engine Light).
I would suggest having a mechanic diagnose your transmission problems sooner than later. If something is malfunctioning, it'll only get more expensive down the road.
Be sure to followup with other questions, and we'll all help as we go. Also, make sure you post your results so others may know what to do if this happens to them.
Good Luck!