Chloe,
As Jezebel said you will have to go to Page-setup and choose Landscape. If
you have but one section in your document all pages will be landscape. So if
you want only one page to be landscape and the rest remain portrait insert a
New section (Insert - Break - section break next page) with you cursor in
the section go to File - Page Set-up, choose landscape and in the apply to
section choose this section.
Or with your cursor on the spot where your new horizontal table will have to
start, go to File - Page-Setup, choose Landscape on the margins tab, in the
apply to section choose from this point on. Word will automatically insert a
section to accomodate your landscape page.
Remember when you are finished and want pages following the table to be
portrait again you will have to repeat the process but choose portrait this
time.
Am I making sense here?