There is not much use in going into detail on how to get your system ready for Internet. Egil Kvaleberg has written an excellent ISP-Hookup-HOWTO for this purpose. You can find this document at http://www.linuxdoc.org/
Most software that the ISP-Hookup-HOWTO refers to is already installed on our system, except software to browse newsgroups. Also take a good look at the section about Sendmail. You might have to do some editing of your /etc/sendmail.cf file.