Ask HN: How does government contracting for small businesses/startups work?

A friend told me about following article: http://www.rollingstone.com/politics/news/the-stoner-arms-dealers-20110316

Given that some businesses win government contracts by default because they are a minority/diverse/small where could I find these contracts?

How would you go about selling a product to the government if you fall in to the category of businesses that are automatically wining these contracts?