Hiding Excel SPreadsheet rows according to the values entered in a cell on the same sheet

The following is something I've lifted from another post as being a suitable solution for something I want to do in a spreadsheet - ie hide certain rows when a cell is set to certain values. The problem is I have no idea how and where to apply it to my spreadsheet. Can you point me in the right direction please. Also - are any of the names here dependent on the name of the sheet I'm applying it to or are they generic? Once I get this in and amended I'm sure it will help me along my learning curve. Thanks

Private Sub Worksheet_Change(ByVal Target As Range)

If Range("A1").Value = "1" Then
    Rows("2:95").EntireRow.Hidden = False
    Rows("3:11").EntireRow.Hidden = True
    Rows("15").EntireRow.Hidden = True
    Rows("19").EntireRow.Hidden = True
    Rows("20:50").EntireRow.Hidden = True
ElseIf Range("A1").Value = "2" Then
    Rows("2:95").EntireRow.Hidden = False
    Rows("3:10").EntireRow.Hidden = True
    Rows("15").EntireRow.Hidden = True
    Rows("29:52").EntireRow.Hidden = True
    Rows("82").EntireRow.Hidden = True
ElseIf Range("A1").Value = "3" Then
    Rows("2:95").EntireRow.Hidden = False
    Rows("3:20").EntireRow.Hidden = True
    Rows("95").EntireRow.Hidden = True
ElseIf Range("A1").Value = "4" Then
    Rows("2:95").EntireRow.Hidden = False
    Rows("8:10").EntireRow.Hidden = True
    Rows("12").EntireRow.Hidden = True
    Rows("14").EntireRow.Hidden = True
    Rows("16").EntireRow.Hidden = True
    Rows("18").EntireRow.Hidden = True
    Rows("20").EntireRow.Hidden = True
    Rows("22").EntireRow.Hidden = True
    Rows("2:60").EntireRow.Hidden = True
End If

End Sub

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It will look for value in A1 in current sheet (where you run macro).
If you want specific sheet use Sheet("Sheet2").Range("A1") instead of just Range(A2")

In this example it would be better to use Case approach rather than IF-else