Modifying Existing Code + Find Range Differences

I have a bit of code that checks the values in 2 ranges for differences, and then prints (in a cell range) the differences between the 2 ranges.
I would like to modify this a little, instead of having the columns hard coded in the module, I would like the user to be able to select the ranges they would like to compare.

Here is what I have for code:

Sub Main()

Application.ScreenUpdating = False

Dim stNow As Date
stNow = Now

Dim varr As Variant
varr = Range("A2:A" & Range("A" & Rows.Count).End(xlUp).Row).Value

Dim arr As Variant
arr = Range("I3:I" & Range("I" & Rows.Count).End(xlUp).Row).Value

Dim x, y, match As Boolean
For Each y In arr
    match = False
    For Each x In varr
        If y = x Then match = True
    Next x
    If Not match Then

        Range("B" & Range("B" & Rows.Count).End(xlUp).Row + 1) = y

    End If
Next
Range("B1") = "Items not in A Lists"
Range("B" & Range("B" & Rows.Count).End(xlUp).Row + 2) = "Items not in I Lists"

'Dim arr As Variant
arr = Range("A3:A" & Range("A" & Rows.Count).End(xlUp).Row).Value

'Dim varr As Variant
varr = Range("I3:I" & Range("I" & Rows.Count).End(xlUp).Row).Value

'Dim x, y, match As Boolean
For Each x In arr
    match = False
    For Each y In varr
        If x = y Then match = True
    Next y
    If Not match Then
        Range("B" & Range("B" & Rows.Count).End(xlUp).Row + 1) = x
    End If
Next


Debug.Print DateDiff("s", stNow, Now)
Application.ScreenUpdating = True

End Sub

I found this code here:

HTML Code: 

Posted by "crazynut"

I suppose I was thinking that:

Set Range1 = Application.Selection
    Set Range1 = Application.InputBox("Select Range 1 :", xTitleId, Range1.Address, Type:=8)
    Set Range2 = Application.InputBox("Select Range 2:", xTitleId, Type:=8)

Was the route I was going to go down. But wasn't sure if that was the best course of action?

Couple of questions:

The input box does not allow me to select the starting point of the second range, I can however type in the start point.
Also, would't this part of the code need to be updated to reflect the users selection?

'Dim arr As Variant
arr = Range("A3:A" & Range("A" & Rows.Count).End(xlUp).Row).Value

'Dim varr As Variant
varr = Range("I3:I" & Range("I" & Rows.Count).End(xlUp).Row).Value

'Dim x, y, match As Boolean
For Each x In arr
    match = False
    For Each y In varr
        If x = y Then match = True
    Next y
    If Not match Then
        Range("B" & Range("B" & Rows.Count).End(xlUp).Row + 1) = x
    End If
Next