cruiser2 - I use LibreOffice which has similar parentage to OpenOffice. The problem you have encountered may simply be that you need to alter the envelope orientation.
This is the route on LO: from a blank document in Writer: envelope/printer/envelope orientation (The envelope orientation options are then displayed.)
Again, using LO, the envelope screen is available under "Insert" on the tool bar.
Hope the above is of some help.