Moonshot0087,
I know on my end I stumbled across the solution and I do hope this works for you as well.
If you are working in Mountain Lion with cs6 I can tell you I couldn't find one of the sets of files because they were in a HIDDEN /library folder in my user directory.
If this is the problem that you are having, make sure first to go to terminal and turn on hidden files (copy this into terminal):
defaults write com.apple.finder AppleShowAllFiles -bool true
Then hold "Alt/Option" and right click "Finder" then click "Relaunch" in the pop up menu.
From there you will be able to find the /Users/"USERNAME"/Library/Application Support/Adobe/Dreamweaver CS6/en_US/Configuration/extensions.txt and /Users/"USERNAME"/Library/Application Support/Adobe/Dreamweaver CS6/en_US/Configuration/DocumentTypes/MMDocumentTypes.xml.
Once you edit those files restart Dreamweaver and everything should work just as expected.