Newbie – How to keep parts of a post dynamic with WP Super Cache HELP!

Hi again, I have now looked at the readme.txt to see how to keep the ebay parts of my page dynamic. I understand that I can use the “dynamic cached content” function/code. Where do I need to put this code in? The function I am looking at keeping dynamic is phpBay where listings will be shown on every post. Do I do this within htcaccess file or where? Apologies if this is really obvious but I don’t know where to put this code in, or indeed what else to include in the code apart from the above.
Thanks for bearing with me……