To complete the installation of Plone: 

- Restart Zope.  This may be done from the Zope Control Panel.

If you are upgrading from an earlier version:

- Go to http://yoursite/manage

- Go to portal_migrations

- Click the Migration tab

- Click Migrate

If you are upgrading from plone 1.0, please read:
http://plone.org/documentation/migration/2.0