How make dreamweaver color the code as php for .inc files

You'll have to add the .inc extension to MMDocumentTypes.xml. You haven't indicated what version of Dreamweaver you're using, or your operating system, so I'll have to guess Windows is your OS from your other questions.

On Windows 7 and Vista, the file is located at:

C:\Program Files (x86)\Adobe\Adobe Dreamweaver CS4\configuration\DocumentTypes\MMDocumentTypes.xml

and on XP:

C:\Program Files\Adobe\Adobe Dreamweaver CS4\configuration\DocumentTypes\MMDocumentTypes.xml

After opening the file, search for PHP. You'll come across this block:

<documenttype id="PHP_MySQL" servermodel="PHP MySQL"
internaltype="Dynamic" winfileextension="php,php3,php4,php5"
macfileextension="php,php3,php4,php5" file="Default.php"
writebyteordermark="false">

Now add the .inc extension into the winfileextension (and macfileextension to be safe):

<documenttype id="PHP_MySQL" servermodel="PHP MySQL"
internaltype="Dynamic" winfileextension="php,php3,php4,php5,inc"
macfileextension="php,php3,php4,php5,inc" file="Default.php"
writebyteordermark="false">

save this file, exit, and restart Dreamweaver.

As of CS5.5 on Windows 7 the file exists twice. Once in the location mentioned by John T, but also in:

c:\Users\USERNAME\AppData\Roaming\Adobe\Dreamweaver CS5.5\en_US\Configuration\DocumentTypes\

If you dont change this file, the color coding won't work.