If you have little knowledge of linux, I would suggest some other distro of linux, other then Slackware. Slackware is my favourite, but it needs some more *nix knowledge if you want to configure it smoothely. You could try Ubuntu for an alternative.
If you really want Slack, this is the closest I know of (older Nagios installation for an older Slack), but it could be useful.:
onlamp.com/pub/a/onlamp/2002 ... agios.html