Start with this. Put it in the Sheet Example module.
Since you are not clear about which values have to be changed to what you must adapt the code yourself.
Code:
Private Sub Worksheet_Change(ByVal Target As Range)
    If Target.Address = "$B$1" Then
        FindNr = Sheets("Table").Columns(1).Find(Target.Value, , xlValues, xlWhole).Offset(, 1).Value
        With Sheets("Example")
            For Each cl In .Range("B4:B" & .Cells(Rows.Count, 2).End(xlUp).Row)
                If cl.Value = FindNr Then
                    cl.Offset(, 1) = IIf(cl.Offset(, 1).Value = "x", "n/a", cl.Offset(, 1).Value)
                    cl.Offset(, 2) = IIf(cl.Offset(, 2).Value = 0, "j/k", cl.Offset(, 2).Value)
                End If
            Next
        End With
    End If
End Sub