Tracking ensures that you are covered as the seller by Listia...that way in case there is a mishap with the shipping or something. It is highly recommended on high credit auctions like this. I think it is 90 cents and is easy to add; just tell the post office worker
I think you have to be on a pc/laptop. Go to "my account" and there should be a link and an FAQ on how to activate it...pretty simple to do, I just forget how as it has been a while since I activated mine :)