Password protecting a post or page is quite simple. All you need to do is look for the Visibility option (which by default is public) in the Publish box and click the Edit link. Once there you have the option to make the post password protected by clicking on the radio button. Once clicked, it will prompt you to put in a password. It can be whatever you want it to be, but if you want others to see what is in this page or post, you will have to share the password with them.