Download windows live mail or your favorite mail program and install it. Windows 7 doesn't come with a default mail program installed. i'm at work now so this link keeps directing me to the XP page. hopefully, it directs you to the windows 7 version, otherwise just google "widnows live mail".
Outlook is now available only in Office. If you have any version of Office you can install it. Thunderbird (http://www.mozilla.org/en-US/thunderbird/) is a popular email client with many features.