How to add pages using code?

Hi,

I use WordPress as a blog/content manager, but adding all of the custom fields and pages manually using the built in editor is a little time consuming. What I’m looking to do is write a plugin that adds a new page to the admin area, and once the form is filled in it automatically adds several pages with their custom fields.

How would I go about adding a page and fields using code in a plugin?

Cheers