Yep, Win-7 doesn't come with an email program, like you're probably used to with older versions.
You have to decide what kind of email 'client' you want to use, Web based, like Yahoo mail, myMSN, or Hotamil, or POP-3, (acct on your desktop), like Windows Live mail, Gmail, or Outlook, and download or install it from a disk.
Then when installed, if you have just the 1 email program, it will be your default. Windows Live mail (In Windows Live Essentials) is the replacement for Outlook Express, and is nice. Lots of features. If you want to get your email from multiple sites, like work, or a friends, or relative's house, then a web based program is the way to go. Can have one of each, or many, but initially keep it simple.