SNMP configuration

hi

I have cisco 3750 switch . i configured it for snmp and i created a community string.
i am using PRTG tool for monitoring. PRTG have 2 sensor (SNMP and SNMP RMON ) . SNMP sensor working fine but i want to use SNMP RMON for deep monitoring . but i dont know to configure switch for this sensor any one can help me

thanks .