how to find html in plugin files

I’m pretty new to this, so apologies if this question is too basic for this forum, but:

I’ve located via firebug some html where I’d like to make a small change in a plug-in (wp-ecommerce) but I can’t find the file where the html actually exists to change it.

I’ve tried following what seems to be the path in firebug, but the names don’t correspond to the actual files. Tried doing a search for some of the html in many of the plugin files, but still can’t find it.

How does one find the correct file to make a change after using firebug?

specifically, I’d like to change the page the “visit the shop” link that my wp ecommerce shopping cart links to. any advice appreciated.
here’s the url: http://g2g.nrgorgeguide.com/order-for-february-14/

thanks in advance for any help!