In the Universal Email wizard, go to tthe body tab and clickthe DW Edit button.
this will open a new Dreamweaver template page for you to design the email. Place your cursor in the Blue Editable region Box, then go to Insert -> WebAssist -> eCart -> Cart Display Manager.
This will add the display Manger to the email body. Go to File -> Save to save your changes and get back to the Universal Email wizard. Then click OK to apply it.