Most printers have some amount of nonprintable area along each
side of the page.
Assuming you inserted a page border in Word, then your border is
probably too close to one edge of the page and is partly in the
nonprintable area. Click on Format | Borders and Shading |
Options, and experiment with either increasing the "from edge"
measurement or decreasing the "from text" measurement until the
border prints.
If you inserted a clipart border in Word, then select the clipart
and resize it so that the clipart is positioned further away from
the page edge.