The My Listia page is where you can quickly access all of your messages, auctions, feedback, fans, etc. You can get there by clicking on your username in the top right corner. You will see a dropdown menu, where you can select My Listia. Alternatively, you can simply click the Listia logo in the top left corner of any page when you are logged in.
All of the things visible on the left side of this screen shot can be accessed from the My Listia page.