It would be somewhere in the Airport Utility interface if it's there, try this link.

This link has a link to a little known Apple utility too, Airport Management Utility.

You can't get to it by router (base station) IP,, if you have an Apple Airport base station.

I don't know why they are not showing up in the sidebar though, did you check Finder/Preferences/Sidebar, Bonjour computers check marked?