List of Resources
http://www.bls.gov/iag/iaghome.htm : an overview of the U.S.'s many industries by category. If you follow the links along the page, you can find much of the information you are looking for.
http://www.census.gov/epcd/susb/2001/us/US--.HTM : will give you the specific numbers for the amount of employees and firms in a given industry.
http://www.census.gov/main/www/industries.html : has a list of every industy's profits in the past 10 years.
http://www.tutor2u.net/economics/content/topics/competition/competition.htm : a site to jog your memory on perfect competition, just in case you forgot what we talked about in class.
http://william-king.www.drexel.edu/top/Prin/txt/Imch/MC1.html : a site to jog your memory on monopolistic competition.
http://www.tutor2u.net/economics/content/topics/monopoly/barriers_to_entry.htm : barriers to entry (for use when deciding if your industry would be a good one to enter)
These websites will help give you a head start, but the meat of your research will have to be refined to the specific industry that you choose. Simple Google searchs as well as using articles and journals in the library will help you find the information you need relating to your industry. Again, if you need help finding useful data, just ask me!