Have you tried a google search?
I found this site:
Which provides the following VBA code which seems to work just fine:
Dim r As Long, mcol As String, I As Long
' find last used cell in Column A
r = Cells(Rows.Count, "A").End(xlUp).Row
' get value of last used cell in column A
mcol = Cells(r, 1).Value
' insert rows by looping from bottom
For I = r To 2 Step -1
If Cells(i, 1).Value <> mcol Then
mcol = Cells(i, 1).Value
Rows(i + 1).Insert
How to use this code:
Go to Extra>Macro>Visual Bacis Editor (Alt+F11)
A new window will open.
Go to Insert>Module
Copy and paste the above code in the great white space.
Close the window.
Back in your excel window.
Go to Extra>Macro>Macro's (Alt+F8)
A new small window will open.
Double click "InsertRows" to see the result of the code.
If something is still unclear then post back.