Open Excel by double-clicking on the Desktop icon or by clicking on the "Start" or "Microsoft Office" buttons, then clicking "All Programs" > "Microsoft Office." Click on "Microsoft Excel." Excel will open with a new spreadsheet.
Type your data into the Excel spreadsheet. For example, if you want to plot sales data for the last three years, place the data from year 1 into column A, the sales data from year 2 into column B, and the sales data from year 3 into column C.
Highlight the three columns of data by left clicking on the top left of the data, then dragging the cursor to the bottom right.
Click on the "Insert" tab, then click "Line." Click on the first line graph icon. Excel will insert the frequency polygon into your spreadsheet.