Getting Page numbers right in Word 2003...

I'd be grateful if some of you could tell me what I am doing wrong with my
page numbers in WORD 2003. I am ending up with page numbers at BOTH the top
and the bottom of a long book manuscript with many separate sections. I
obviously don't want them in BOTH places & would prefer to have them at the
bottom, out of the way of my headers. This could be because I originally
inserted page numbers from the INSERT/Page numbers command but am now using
headers, though I haven't so far used any of the page numbering features of
headers & footers.

Also, some of my chapter titles as headers are printing over the page
numbers, making a mess of both.

I expect the answer is simple, & my problem is due to my just beginning this
long formatting task & not having yet digested all the rules. But any help
you could provide could save me a lot of time.

Thanks in advance!

alex