I just got my account in the Computer Science department, I've logged on to Windows, but I cannot read my email.
Email sent to your CS email address is forwarded to your UA email address, which is <your UA NetID>@email.arizona.edu.
You can read email by using your favorite browser (Internet Explorer, Firefox, Opera, Safari, etc.) to go to webmail.arizona.edu and log on using your UA NetID. Or you can set up Thunderbird, which is installed on every Windows and Linux machine in the CS department, and which you can download and install at home. See Using Thunderbird to read CS email for instructions on setting up Thunderbird.
The web page http://ccit.web.arizona.edu/index.php?id=email provides information about how to get started with your UA email account, how to use Webmail and other email clients (such as Thunderbird or Pine) to read UA email, and how to use Listservs to send email to groups of users.
See also Computer Accounts and Keycards for information about computer accounts in the CS department.