When you open Yahoo! Mail, a What's New page opens in the main window. If you have any new messages, the word "Inbox" followed by the number of new messages appears below the What's New page. You can click this or you can click "Inbox" at the top of your folder list in the navigation bar to the left. You can also click on any other folder if you're looking for a message that is somewhere other than your Inbox.

A list of the emails in your Inbox(or the folder you clicked) opens in the main window. Click anywhere on the info line (Sender, Subject, Date/Time) of the message you want to read, and the message will appear in the "reading pane" below. This is a preview window. You can also double-click the info line for the message, and the message opens in the entire main window, under a new tab. This gives you more room to read the message, but it also covers up the sub-window that listed the folder contents.

After you've read a message, the message's info line no longer appears in bold and only unread messages do.