When working with SQL Server most of the times the example queries that are provided in articles are based on the sample databases available in SQL Server 2005 / 2008.
If you have missed installing the Sample Databases when installing SQL Server, all you need to do is download the sample databases that are available at Microsoft Codeplex Website. There are databases available for SQL Server 2005 and SQL Server 2008.
Additionally you can look at the one of my articles to Install a sample Database in SQL Server 2005
— Bru Medishetty