You can set up as many different headers and footers as you need to use in your document; the limit is the number of pages. All headers and footers are associated with a page, where the caret was in the document when they were created. Usually they will also be associated with a page break, either at the start of a document or the start of new chapters.
To add a different header or footer to a page:
If you have more than one header or footer set up you can choose which you use on each page using the Pages dialogue box. This presents a list of options; each header or footer is listed by the number of the page it was first set up on.