linux system mail - information overload

[Hadron Quark]

Could some kind soul please nudge me in the right direction to set gnus
up to read my Ubuntu "system emails". By these I mean the ones in
/var/mail or in /var/spool/mail - A google provides so much information
I cant really get started with any confidence and am even lost at
differentiating between the two.

I already have fetchmail using procmail to publish incoming pop3  mails
and mailing lists to maildir format.

How to see "localhost" email?

Any terminology/education much appreciated.