Graham has assumed that you want to change the actual paper size (width), but I'm guessing your book is directing you to Zoom to Page Width. I gather that you've found the Page Width button in the Zoom section of the View tab, and that actually does what
you want, but your book is directing you to select the radio button for "Page width" from the Zoom dialog and then click OK. You can open the Zoom dialog by double-clicking on the Zoom percentage next to the Zoom slider on the right end of the status bar or
by clicking the Zoom button on the View tab.
Why Microsoft removed the predefined tool bars in Office 2010 is beyond me.
Now every computer I sit at, I have to customize the interface button by button instead of just switching a toolbar on or off.
It's a time consuming waste of time and I'm sure very confusing for the people who can't figure out where the button is they're trying to add has gone to - or how to add it to their "custom" toolbar.
Whoever redesigned the interface should be kept far away from doing it again.
My department at work has >1000 users who are all very unhappy with the new interface, and I know another major health care organization where they're moving to OpenOffice because of this and similar reasons. Microsoft should fix this menu/toolbar mistake quickly.
******@health.nyc.gov