create a password before sending files via e-mail xls file

Dear All

Please help my user request when sending attachments to xls file via email, I must not understand the password at all

Can you explain better what you're trying to do?

You mean how to create a password protected excel?

Because you mention adding files to XLS via email and I think you are mixing something.

Dear Nuno Reis,

You mean how to create a password protected excel? --> yes 

how to create password sheet xls?