Select this command to start editing a new stencil file. Edit the stencil in the canvas window just like a normal OmniGraffle Document; the preview in the stencil viewer updates as you work. Save the file wherever you like, but if you save in the Stencils folder in one of your Application Support locations, the stencil will be available from the Stencils menu.
Edit Stencil
Open a canvas window on the stencil you have open, so that you can change it; if it's a stencil that came with OmniGraffle, you'll edit a copy of the stencil instead of the original.
Get More Stencils...
This delivers you to the OmniGraffle web site, where you can download mounds of exciting new OmniGraffle stencils.