When you open Yahoo! Mail, a What's New page opens in the main window. If you have any new emails, the word "Inbox" followed by the number of new emails 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 an email 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 email you want to read, and the email will appear in the "reading pane" below. This is a preview window. You can also double-click the info line for the email, and the email opens in the entire main window, under a new tab. This gives you more room to read the email, but it also covers up the sub-window that listed the folder contents.

After you've read an email, the email's info line no longer appears in bold and only unread emails do.