Benutzername und Passwort

Usually you would do this using some kind of server side language like php or node. You can do it through your websites control panel if you have access to one but its not a very elegant solution, just cheap and cheerful, if that works for you.

There's plenty of php solutions previously posted in this forum that provide the code for webpage protection if you search.

Have a look at 

https://help.dreamhost.com/hc/en-us/articles/216363187-Password-protecting-your-site-with-an-htaccess-file

Edit: Oops, sorry Nancy, I did not see your reply when I wrote mine. Just goes to show though, that great minds think alike 👍

Dreamweaver has no built-in page protection features.  That's a server function. 

If your hosting plan includes c-Panel  you can password protect a page or a folder of files by logging in to your server account.  Ask your hosting provider for more details.

Or use .htaccess and .htpsswd files to limit access to content on your server.

https://help.dreamhost.com/hc/articles/216363187-Password-protecting-your-site-with-an-htaccess-file

Hope that helps.