Preamble or Prerequisites may be appropriate for information that leads in to structured information but, if you are writing structured information, your information should be structured - into sections...
If you are trying to cross-reference within a technical or structured document, I would recommend giving your sections meaningful titles and cross-referencing the Sub-heading, for example:
"See: 1.2 Selecting your widget"
I would use "See:" if the link is within the document, and "Refer:" if I was directing the reader to another source, a book or WWW., etc.
If you make your headings meaningful, it will help the reader decide if they actually want or need to go there, for example:
"Introduction" - Introduction to what? Do I really need to read this??
Where as:
"Selecting the correct Widget" - Conceptual material. How do I choose my widget?
"Join widgets to sprockets" - A Task or process... How do I do it?
"Types of Widget" - Reference material. Which is the right widget for my application?