Numbering thesis paragraphs

I'm writing this blog while my Word crashes. :(

I thought I'd try again to number the sections within each chapter, like so
2 Literature review
2.1 Introduction
2.2 public sector procurement

I found instructions at http://www.shaunakelly.com/word/numbering/numbering20072010.html
and followed them down to modifying the style for my second level headings, where it has crashed. BANG, WALLOP! Silence.

Oh, bother! I'd really like to list my headings like this because I think it would make it easier to work out where you are in the middle of a long chapter.