To modify an existing file type
Open Folder Options in Control Panel.
Click Start, and then click Control Panel.
Click Appearance and Themes, and then click Folder Options.
On the File Types tab, click the file type you want to change, and then click Advanced.
If necessary, modify the file type description, and click Change Icon to change the file type icon.
Under Actions, click the command you want to modify, and then click Edit, Remove, or Set Default. Click New to add a new command to the Actions list.
After you specify a new action, the corresponding command appears on the menu when you right-click a file with the associated extension.
In the New Action dialog box, you can click Browse to find the program you want to specify for the action.
All files that have the file name extension will use the icon and commands you specify.