Help with where to put coding

[Crackers]

Yesterday I was advised by 'Smart' on placing a certain code, as follows:

In the after update trigger of the combo box you can do the following

If YourCombobox = "-" Then
yourtextfield.ForeColor = vbRed
Else: yourtextfield.ForeColor = 0

End If
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Please forgive my ignorance but where do I put this code... on the line for 'after update' or in the code builder. If it is the latter, how do I begin the code because it has Private Sub and End Sub. I am obviously no expert but I'm just trying to plod along and learn as I go.
Your help is gratefully accepted.

 

[wazz]

between Private Sub and End Sub.

Private Sub cboName_AfterUpdate()

   If Me!YourCombobox = "-" Then
      Me!yourtextfield.ForeColor = vbRed
   Else
      Me!yourtextfield.ForeColor = 0
   End If

End Sub