Was this created with Design Extender? or the old Power CMS? in the tutorial description, make sure you read the note:
*Note: Only users with Design Extender should follow these upgrade steps. Users who purchased the PowerCMS Solution Pack, should not follow this tutorial.
for an older site that was initially created with Power CMS, you will need to rebuild the CMS using Design Extender to get in page editing functionality. there is not an upgrade path for older Power CMS.