I'm guessing you already have a email address and know the pop/smtp server addresses? ANd your username/password? Then its easy as pie. Just start kmail or mozilla-mail and figure out how to add an account. (With mozilla mail its just clicking on Edit > Mail And Newsgroups Account Settings.
If im worng about the above and you actually want to host your own email server, then its a little more difficult. I dont know how much help this would be, since you may not be using slackware, but I followed
this to get my email server working.
