Answer:
First, you need to start the OSPF process by executing the command:
Router (config)# router ospf {process-ID#}
Then, you have to instruct the router to advertise the networks that are directly linked to it by entering this network command with the area ID number for that network:
Router (config-router)# network {192.168.10.0} {255.255.255.0} area {0}
