locking cells in a sheet when a workbook is saved

i'm a beginner in Vb, but i created a nice sheet and wanted to add this option to it it's a work book having 33 sheets,each sheet is password protected,what i want is when an employee goes to sheet 1,edit it and then save, certain range of cells will be locked so he'll not be able to edit again this has to come with a msg when he save, the file will be locked for editing, are you sure you want to proceed

thanks for your help

well as i said i'm a little bet beginner in that, so what should be
"your code here"
the code to lock certain range when the file is saved
sorry to bother you with that