Click on the Extensible MCMS Page Navigation Web Part and drag it into any Web Part Zone on the left-hand side of your screen. You should see the following:
If the Extensible MCMS Page Navigation Web Part does not appear in the Virtual Server Gallery, redeploy the Web Part to the server using the method outlined in Executing the Deployment verifying that no errors occur during the stsadm.exe –o addwppack command.
If the error message An error has occurred appears, verify the trust level settings in the Web.config are sufficient.
Another error that frequently occurs is A
Web Part or Web Form Control on this Web Part Page cannot be displayed
or imported because it is not registered on this site as safe. If you see this, verify the contents of the Manifest.xml and NavigationWebPart.dwp files for typos.