if you are using WPM, Web page Maker, you can lock it by right clicking on the page and choose the option lock.

There are a variety of methods you can use, PHP, user validation, there are numerous scripts out there, free and paid,

One of the quickest and probably fastest methods, (if you have Cpanel) is to just protect a directory,



Just click on Password Protect Directories and your off to the races.

The easiest way is the .htaccess for Apache servers. Or you can google for some scripts.

do you using Wordpress?
because wordpress already have it built-in ..

go WP