TC Desktop - How to make changes to variable for Data Driven Loop input file.

TestComplete 12.60 Desktop.

I created a project, recorded a Keyword test and applied a Data Driven Loop to the Keyword Test. I converted the Keyword test to Script [VBscript].  Everything has been working great. I deleted the original Keyword test since I am using the VBscript to execute my test.

 

Now I need to add some columns to my XLS Data Driven input file and I believe I need to update the variable associated with me Data Driven input file. 

 

I cannot figure out how to get to the variable definition for the variable associated with the Data Driven input. Help indicates to select the Variables Tab. I do not know where that is.

 

I appreviate any assistance that can be provided.