Click on a cell to select it, and then click on the Set button to specify the cell address for the value, goal, or warning.
 

Excel Web Access - Use the Excel Web Access to interact with an Excel workbook as a Web page.  Excel Web Access

 
 
Select a Workbook
Select a Workbook To display a workbook in this Web Part, you must first select the workbook.

To select a workbook, open the tool pane, and then edit the Workbook property.
Click here to open the tool pane.

How do I connect this Web Part to a workbook?

Cell Address for Indicator Value:
Cell Address for Indicator Goal:
Cell Address for Indicator Warning: