Hi Jim,

Adding a new line to an existing graph in Excel 2007 is a simple process. Here are the steps you can follow:

1. Open the Excel file that contains the graph you want to modify.
2. Click on the graph to select it.
3. Click on the "Design" tab in the ribbon at the top of the screen.
4. Click on the "Select Data" button in the "Data" group.
5. In the "Select Data Source" dialog box, click on the "Add" button under "Legend Entries (Series)."
6. In the "Edit Series" dialog box, enter the name of the new series in the "Series Name" field.
7. In the "Series Values" field, click on the icon to the right of the field.
8. Select the range of cells in your spreadsheet that contains the data for the new series.
9. Click "OK" to close the "Edit Series" dialog box.
10. Click "OK" to close the "Select Data Source" dialog box.

Your new line should now be added to the graph. You can customize the appearance of the line by selecting it and using the formatting options in the "Format" tab of the ribbon.