Need to modify macro to also create backup of original file

Hi all, I need to modify the macro bellow to also create a backup copy of the original workbook,

1- Once the macro is run it will save the current workbook (that is done by the code already) and than close it.
2- Create a new file with same file name but add today's date, (these files will be kept in same folder)
3- After 3 backups override the first one, than the second and so on...!

Can this be done in VBA?

NOTE: Current Macro saves and closes the workbook but it leaves open excel application with all commands ghosted, I would like it to close workbook and excel also......

Sub SaveExit()
Dim Workbook As Long

    ThisWorkbook.Save
    ThisWorkbook.Close
End Sub

Thank you all in advance