There is just one agent to turn on called
'Level 1 Scan'
It may take 2 runs to complete the full audit.
So open the database, then from the Notes Client Menu, View \ Agents.
You need to enable the agent. Ideally you also need to sign the agent with an ID that has access to all the databases on the server, otherwise some of the results may come back a bit short:->
You may also want to open the agent and check the schedule, maybe setting it to once a week?