The least complicated way to reset or skip numbers is to give a number argument to the .bp (break page) command, and then choose it as a format note, which forces a page break and numbers the new page as you specify (you can use Preview to see where the pages break naturally, and put the command there). For example, to skip from page 2 to page 6, put the following command where page 2 ends:
.bp 6 (forces a page break and numbers the new page "6")then highlight, and choose Format Note in the Region menu card. Forcing numbering of the first page. You can force a page number to appear in the default position on the first page, which normally does not happen. Simply put the command
.bp1at the top of the document, before any text, and then highlight it, and again choose the the Format Note option in the Region menu card. You will get a blank page, un-numbered (which you have fooled troff into believing is the first page of the document), and the first page of text will be numbered 1.