Password protected pages

I’m new to this my first time constructing a website and I must say I’m glad I have tried it , getting hook on it
Question. A password protected page , I’m trying to have a log in page for certain item , like a page only certain people can access (password protected )

I have placed a password on a page when I open the page and then log off the page , hit refresh on site go Bach into the site like a new user would do The page is still open
I need it to close automatically if a person leave the page is the possible