Adjusting canvas size

[rhkramer gmail com]

Background: I'm new to Dia, but, from what I've seen so far, it looks like I 
can use it for my current purpose--creating a (multi-page) state diagram.

I did use Visio quite a bit but that was 15+ years ago.

My current issue is trying to figure out how to (or if I need to) adjust the 
canvas size--when my state diagram is done, I'd expect it to have a mostly 
vertical orientation--something like 2 (8.5x11) pages wide (i.e., horizontal) 
and 8 pages long (i.e., vertical).

The canvas I see when I start up Dia or start a new diagram is 5 pages wide 
and 2 pages long.

How do I adjust the canvas?

I've tried looking at the Dia manual, and googling, (including the mail 
archive), but so far haven't found anything.  (I may be using a poor choice of 
searchwords--my typical search has been [Dia canvas size].)