Detecting Change In Spreadsheet - Which Cell

How to detect a change in a spreadsheet, but how do i etermine on which cell the change happened?

Basically, I need something like this, if in the range of b1:b30 a cell is changed by the user, let say B??, then change or modify (via a subroutine) cell A??.

Code:
Private Sub Worksheet_Change(ByVal Target As Range)
'
' detect which cell in the range b1:b30 changed
' then modify the cell to the right (or left) of the changed cell
'
End Sub