If you don't wish to read your mail on the internet through webmail, you need to have an e-mail client/program installed. Once you've got this you will need to set this up. The different types of programs will generally have to be set up in the same way, by entering the incoming and outgoing mail server.
At NTNU we have one incoming mail sever, imap.stud.ntnu.no.
The difference between pop and imap is that if you use pop, the e-mail client will download all e-mail to your local computer and delete it from the server. Imap will read the mail on the server, only the list over your e-mails on the server will be transferred to your local computer. POP is no longer avalible at NTNU.
At NTNU the outgoing mail server is called smtp.stud.ntnu.no.