This should be automatic, as Word's default is to continue numbering from
the previous section. If you're seeing something different, then you've
evidently at some point restarted numbering from 1. Unfortunately, now
you've got page numbers restarting in sections that are inaccessible from
the Header and Footer toolbar. There are two possible approaches:

1. Remove all section breaks (or at least the ones in the problem area), set
the numbering to continue from the previous section (using the Format Page
Number button on the H&F toolbar), and then reinsert the breaks.

2. Place the insertion point in the section where the page numbering problem
starts and go to Insert | Page Numbers... Press the Format... button and
choose "Continue from previous section." Press the OK button in the Page
Number Format dialog, but be careful to press Close rather than OK in the
Page Numbers dialog to avoid inserting additional page numbers.

--
Suzanne S. Barnhill
Microsoft MVP (Word)
Words into Type
Fairhope, Alabama USA
Word MVP FAQ site: http://www.mvps.org/word