Powering on Password in Bios

How do I put power on password in the bios so the machine won’t load the OS until the password is entered.

Also, When I click on an attachment in my e-mail, it downloads correctly. But then the open with box open and says: Click the program youwant to use to open the the file with. Sometime the attachment is a photo and sometimes the attachment is text. Which program should I use?