Need Help with creating a Sorting Macro

I want to use a macro to sort when the number of selected rows change. Here is my code for sorting. How do I change it so it will work only on the rows I select? So for example, in my code below I selected A9:D17 but this changes throughout the worksheet in sections that need sorting. Is this possible to do with a macro? Thanks.

Sub sorting()
'
' sorting Macro
'

'
    Range("A9:D17").Select
    ActiveWorkbook.Worksheets("Sheet1").Sort.SortFields.Clear
    ActiveWorkbook.Worksheets("Sheet1").Sort.SortFields.Add Key:=Range("D9:D17") _
        , SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
    ActiveWorkbook.Worksheets("Sheet1").Sort.SortFields.Add Key:=Range("C9:C17") _
        , SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
    ActiveWorkbook.Worksheets("Sheet1").Sort.SortFields.Add Key:=Range("B9:B17") _
        , SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
    With ActiveWorkbook.Worksheets("Sheet1").Sort
        .SetRange Range("A9:D17")
        .Header = xlGuess
        .MatchCase = False
        .Orientation = xlTopToBottom
        .SortMethod = xlPinYin
        .Apply
    End With
End Sub