If you tried to add an item to the cart and it is showing as empty your browser may not be set to accept session cookies. If you are using Internet Explorer you can go into Tools, Internet Options and click on the Privacy Tab. Changing the setting to Medium High will allow your browser to accept a session cookie.
A session cookie is just a randomly generated session Id that helps the web site keep track of your shopping cart through the purchasing and checkout process. No discernable information is transmitted in this cookie and it only lasts until your browser closes