If you are new to data modeling in Excel and the Power Pivot add-in, you probably want to get started mashing up some sample data in a workbook right away. A great place to start is with Sample Data for Power Pivot, available at the CodePlex website. This is the same sample data used in the Power Pivot tutorial, and in examples in many of the Data Analysis Expressions (DAX) reference topics.
Tip: Sample data is packaged into a single .zip file so that you can get all of the files in one download. You can find downloads in the Downloads folder on your computer. To unzip the files, right-click the filename and choose Extract All.