[c-nsp] monitoring using Nagios

[teklay gebremichael]

hello,
i installed nagios 3 to manage some of my services and hosts.
i have installed nagios on debian lenny 5 OS. currently the default services are running and i can't monitor remote hosts/services.
i was trying to read about the plugins that nagios needs to monitor remote hosts and services.  and i decided to use snmp plugins so that i can monitor almost every thing about the snmp enabled hosts. 
Can any one help me on what procedures do i have to follow to enable and configure snmp on the client hosts and the nagios server. and if posible a documentation on how i can define services and commands using the snmp plugin.

thanks in advance.
Teklay