Right click on the folder and click on Properties
Click the Customize
tab. (See screenshot below step 4)
3. To Customize the Folder Preview Picture
A) Click the Choose File button. (See screenshot below step 4)4. To Restore the Default Folder Preview Picture
WARNING: Only check the Also apply this template to all subfolders box if you want this preview picture for all of the subfolders in this folder to. You can change them individually instead if you wanted to or not at all.
B) Go to step 5.
A) Click the Restore Default
button. (See screenshot below)
B) Go to step 7.
Navigate to the location of the image you want to use. (See screenshot below)
Select the image and click on Open
Click on OK
to apply. (See screenshot below step 4)
NOTE: You may need to press F5 to refresh the window to see the new preview picture you selected.
If for some reason the selected preview picture will not show on the folder, then try this:
A) Do step 2 and 3 in this link: How to Hide or Show Hidden Files and Folders in Vista
B) Open the folder you want to change the preview picture for.
C) Right click on the faded (means it is a hidden file) Desktop.ini
file (if you have one) and click on Delete
NOTE: The Desktop.ini file will be automatically be regenerated the next time you make a change to the folder.
D) Clear the thumbnail cache
E) Rebuild the icon cache
F) Now try the above steps again.