what is a bill?
what is a green paper?
what is a white paper?
http://www.socialstudiesforkids.com/articles/government/howabillbecomesalaw.htm
http://en.wikipedia.org/wiki/White_paper
http://en.wikipedia.org/wiki/Green_paper
As with all Wikipedia search results, be sure to check out all the external links and further references at the bottom of each Wikipedia page.