I am trying to configure SNMP agent as per the below link.
http://www.net-snmp.org/tutorial/tutorial-5/toolkit/mib_module/
The steps you followed seems to be correct. To confirm if the nstAgentModuleObject is correctly registered, start the snmpd with logs using the following command: snmpd -f -Lo0-6d -DnstAgentModuleObject
Also make sure you place the MIB file in the correct directory (from where the snmpd searches for MIB)