Word 2007 Default Envelope

Could you please help me. I have just converted from Word 2003 to Word 2007 and need to set up our companies envelope.

We use a DL size envelope that has a default return address which includes the company logo.

I have created the envelope by adding it to a blank document and adding the art, font preferences etc….but can’t figure out how to make this envelope the default template.

In word 2003 I saved it as envelope1. How do I do this in word 2007??

Many thanks