What you were told was both (a) incomplete and (b) not entirely correct.

a. Inserting a section break doesn't change anything; it merely makes change
possible. In order to effect the change, you have to put different content
into the header/footer of one section or another. But before you can do
this, you must unlink the header/footer in the second section from the ones
in the first section, using the Same as Previous or Link to Previous button
on the Header and Footer toolbar. For more on this, see
http://sbarnhill.mvps.org/WordFAQs/HeaderFooter.htm

b. It is possible to vary the content of headers and footers without section
breaks using the StyleRef field; see
http://sbarnhill.mvps.org/WordFAQs/StyleRef.htm

You can have up to three different headers within a section. You can have a
different header/footer for the first page; you can have different h/f on
even and odd pages.

Any of these can appear to be different on different pages even though it is
the same header - using conditional fields and StyleRef fields.

Take a look at: How to set up letterhead or some other document where you
want one header on the first page and a different header on other pages.
http://www.addbalance.com/word/headersfooters.htm This gives step-by-step
instructions. (It also has the following links)

Some other pages to look at:

Letterhead Tips and Instructions
http://sbarnhill.mvps.org/WordFAQs/Letterhead.htm

Letterhead Textboxes and Styles tutorial
http://addbalance.com/word/download.htm#LetterheadTextboxesAndStylesTutorial

Template Basics
http://www.addbalance.com/usersguide/templates.htm

How to Create a Template - Part 2 - essential reading
http://www.mvps.org/word/FAQs/Customization/CreateATemplatePart2.htm

Word "Forms"
http://www.addbalance.com/word/wordwebresources.htm#Forms and

Word for Word Perfect Users
http://www.addbalance.com/word/wordperfect.htm if you are coming from a WP
environment (or even if you are not).

Hope this helps,