What does it mean when you have to prepare closing entries for the end of the year when my small business has?

a $6,600 payment on the long term notes payable during 2010. The notes receivable are due May 1, 2011. Also I have invested $50,000 cash early in 2009. I have the adjusted trial balance for my company as of December 31, 2009. What should I look for when I am doing the closing entries? Is long term notes payable for more than five years and what exactly is notes recievable? If someone could help or explain or even give me a sight to look at and study that would be great. Thanks.