Here is the down and dirty on headers and footers:
http://www.addbalance.com/usersguide...ooter_settings

To do what you want will probably require a next-page section break at the end of the page before you want the changes. This is under breaks on the Page Layout tab.

Often what is desired is to change the header/footer to reflect new content in the body of the document. That is best handled using a StyleRef Field instead of a different header or footer.

Your situation may be addressed by How to set up a document with front matter.