I am trying to build a spreadsheet containing cells with 4 different
background colors. Red, yellow, green, and white. I want to graph the
results of the spreadsheet based on background color for each cell. I
extracted the following formula via another discussion but do not know how to
use it (call it or invoke it).

Function BackColour(r As Range)
Select Case r.Interior.ColorIndex
Case Is = 6 'Yellow
BackColour = 1
Case Is = 4 'Green
BackColour = 2
Case Is = 3 'red
BackColour = 3
Case Else
BackColour = "Not Defined"
End Select
End Function

Can someone tell me how to apply this and use the calculated results in a
graph? Thanks.