running a macro when specific text is entered into a specific cell

Hi, I am trying to run a macro when I enter specific text into a specific cell. as you will see I am a complete novice at this, any help would be gratefully received.


This is what I have tried, amongst other things, without any success.

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

Dim rng As Range, cell As Range

    Set rng = Range("F7")

        If cell.Value = "BLAH" Then
        Run Macro1
        End If
        
End Sub

Best Regards

DeeK