You can also access the UCC, including the Official comments, at http://www.law.cornell.edu/ucc/2/overview.html.
You can do so by accessing http://www.nccusl.org, the site of the National Conference of Commissioners on Uniform State Law. You also may find it beneficial to look at http://www.ucitaonline.com/, which will give you information about UCITA, as well as http://www.uetaonline.com/docs/pfry700.html/, which will acquaint you with UETA. To learn about the United Nations Convention on Contracts for the International Sale of Goods, go to http://www.uncitral.org/en-index.htm.
You can check your understanding of the elements of a contract by going to the 'Lectric Law Library's Laypeople's Law Lounge at http://www.lectlaw.com/lay.html/ (use the "contracts" link).