To use the stationery you've downloaded, open Microsoft Outlook and click the Inbox icon. On the Actions menu, point to New Mail Message Using, and the click the stationery you want to use. If the stationery you want is not listed, click More Stationery, and then in the Stationery box, select the one you want to use.
When you install stationery, the image files (*.gif or *.jpg) and the *.htm file are stored in your Stationery folder (by default this is :\Program Files\Common Files\Microsoft Shared\Stationery). Stationery is only available if you use HTML as your email editor.