open ctp file in dreamweaver

There are ultimately 3 files that you need to edit. The first two are located in the folder that you installed Dreamweaver, in my case this is "C:\Program Files\Adobe\Adobe Dreamweaver CS3\configuration" although I'm using the latest version of Dreamweaver previous versions also have a "configuration" folder so go there.
Open up "Extensions.txt" and on the first line at the very end add THTML and CTP separated by commas, so the line should read:

,MASTER,THTML,CTP:All Documents

Similarly add these two extensions to the ":PHP Files" line.

PHP,PHP3,PHP4,PHP5,TPL,THTML,CTP:PHP Files

Next open the "DocumentTypes" folder and edit the "MMDocumentTypes.xml" file, just open it up using notepad or wordpad. Search for the line which has an id "PHP_MySQL" and add the THTML/CTP file extensions to both the "winfileextension" and "macfileextension" so the line should read:

winfileextension="php,php3,php4,php5,thtml,ctp" 
macfileextension="php,php3,php4,php5,thtml,ctp"

The final file is another version of the "Extensions.txt" which is located in your "Documents and Settings" Folder in my case this is "C:\Documents and Settings\James\Application Data\Adobe\Dreamweaver 9\Configuration" just add the very same things you inserted earlier.