Partly because of a ruling from the European Court (which stated that Microsoft's practice of incorporating their web browser and email client into their operating system was anti-competitive) and probably partly just because they like to make every new version of Windows 7 harder to use than the previous one, Microsoft has not included an email client within Windows 7.
Use the solutions here, or (probably far better) download and use Thunderbird:
http://www.mozillames...om/en-GB/thunderbird/
Once you've got an email client you'll obviously need to configure it for use with your email account(s). If you need help, please post again, telling us what the last part of your email address (i.e. the bit after the @ sign) is.
Chris