Most users will probably use e-mail more than anything else. It will be a primary means of communication between faculty, staff, and students. It is a good idea to check your e-mail at least twice a day to make sure you don't miss out on anything important. Your e-mail address will be username@tunl.duke.edu. If you are sending mail to someone else at TUNL, you only need include their username. In addition, various mailing lists are maintained. To send mail to all the REU students for instance, you could use the tunl_reu mail alias (tunl_reu@tunl.duke.edu).
There are numerous mail programs available. No one program is right for everyone. You just have to keep trying until you find one you like. Two of the most popular are listed below.