Unhide Excel Sheets Using Command Button

Hello - thanking you in advance,

Does anyone know the VBA code so when a User opens-up an Excel Work Book File, the User is required to acknowledge a Confidentiality Agreement on, say, User Agreement Sheet by clicking a command button which then opens-up the remainder of the confidential sheets. I am not talking about a password, but that could be an added layer of security.

Thanks if you can assist.
David