On this page you will find a lot of information, some of which can be quite dense.
I've broken the industry research into (hopefully) digestable chunks using your assignment as guidance. In the top center box you will see links to pages that will help you identify the industry code that best matches your small business. There is a tutorial in the box below that will walk you through the research, step by step.
Below you can download step by step tutorial on how to find your NAICS and SIC Codes. There is also a tutorial on locating federal regulations regarding your industry.