Macro to Mark Text with Index Codes

[MyUserName123]

Hi, I'm trying to write a macro that will go through an entire document, find any text in red font and mark that text with an index code. I've tried many different variations of the code below, but nothing works correctly. This latest attempt just inserts blank index codes at the top of the document, one for each instance of every word in red text. I clearly have no idea what I'm doing. Can anyone help? Thank you in advance for any information.

  Sub MarkIndexMacro()
  Dim MyRange As Range
  Selection.HomeKey Unit:=wdStory
    Set MyRange = ActiveDocument.Range
      With MyRange.Find
        .Font.Color = wdColorRed
        Do While .Execute
        ActiveDocument.Indexes.MarkEntry Range:=Selection.Range, Entry:=Selection.Range.Text
           Loop
      End With
  End Sub