You need a text or XML file containing the data for your product(s).
You need a Google account, of course, and to familiarise yourself with the Google Merchant ToS (Link hidden: Login to view
) and the Google Product Search policies (Link hidden: Login to view
Once you've done that, check out Google's own tutorial on product feeds (Link hidden: Login to view
.) It contains all the info you need, particularly an in-depth explanation of the various values you can add to your feed to describe and highlight your product(s).