For new installations:
  edit ${MY_INSTALLDIR}/pmwiki/local/config.php to suit your site setup

Also read the release notes for any other upgrade notes at:
  http://www.pmwiki.org/wiki/PmWiki/ReleaseNotes

And the "Initial Setup Tasks" page:
  http://www.pmwiki.org/wiki/PmWiki/InitialSetupTasks