G'Day Danalynn,
Be aware that a watermark object (picture or text) is
anchored in the Header area.
A general answer would be:
1. Make sure that you use section breaks to separate
the sets of pages that require differing Watermarks
(including sections with NO watermark).
2. Insert the Watermark you would like for any section
- initially it will be the same throughout the document.
3. Double-click, and modify, the Headers so that each
section does NOT have 'Same as previous'.
4. Move to the (in your case) first section, double-click its
Header - you will now be able to 'select' the watermark
with a single (Left-)click.
5. Delete the Watermark (OR Right-click, choose 'Edit ...'
and modify the Watermark for that section).
6. Repeat for the other sections until you have whatever
Watermark you want (including NO Watermark) in each
section.