You need a macro to do the clearing. Here is the new macro:
Private Sub Worksheet_Change(ByVal Target As Range)
If Intersect(Target, Range("E12:E500")) Is Nothing Then Exit Sub
If Target.Value <> "C" Then Exit Sub
Application.EnableEvents = False
Target.Offset(0, 9).Copy Target.Offset(0, 10)
Target.Offset(0, 9).Clear
Application.EnableEvents = True
End Sub
You don't need to be an expert on VBE.
Because it is worksheet code, it is very easy to install and automatic to use:
1. right-click the tab name near the bottom of the Excel window
2. select View Code - this brings up a VBE window
3. paste the stuff in and close the VBE window
If you have any concerns, first try it on a trial worksheet.
If you save the workbook, the macro will be saved with it.
To remove the macro:
1. bring up the VBE windows as above
2. clear the code out
3. close the VBE window
To learn more about macros in general, see:
http://www.mvps.org/dmcritchie/excel/getstarted.htm
To learn more about Event Macros (worksheet code), see:
http://www.mvps.org/dmcritchie/excel/event.htm