What version Publisher?
If you are using 2007, in page setup select *create custom page size*. Type 11"
width - 6"Height. Give the setup a unique name.
Is your paper 11 x 6? If it is you will have to setup your printer for a custom
size too.
If you simply setup your page for 11 x 6 without setting up your printer, you
will have to cut your creation to size. If you are intending to cut your
publication, you would be better off creating on a regular size paper so you
will only have to do one cut.
