MS Excel how to create a macro to find duplicates and highlight them?

Question

How can I create a macro in MS excel to find duplicates in a spreadsheet and highlight it

Answer 1

Sub Macro1()

    Dim Counter As Integer

    For Counter = 1 To 35

        'Cells.(X,Y) X = number, Y = Letter i.e D5 Cells(5,4)
        firstValue = ActiveSheet.Cells(Counter, 3)
        SecondValue = ActiveSheet.Cells(Counter, 4)

        If firstValue = SecondValue Then
            Rows(Counter).Interior.Color = RGB(255, 10, 10)
        End If


    Next

End Sub