how to take excle file backup automatically and put password on excel file

Automatic Backup (.XLK) when File is Saved (#auto)

Setting up for automatic backup of a file.  (on a single file basis, not global)

• Save the file
• Save As (F12 key), then on the Save As Dialog menus: Tools --> General Options, check “Always create backup copy”.  Answer “Yes” when prompted to replace the old document.  Your new document is identical except that the new one saves a backup each time you save the file.

Now, as to the backups: they are always one save behind the original document.  Excel backups have the original name and the suffix .xlk (with a displayed filetype of “Microsoft Excel Backup File”), and will appear in the same folder as the original.  With the Excel backup you can use Autosave and backup simultaneously.