Know your stuff...
Willy says this isn't rocket science and indeed, from the users point of view adding themselves to the assigned htaccess file is very simple however as a web master one should be very aware of security issues and have a basic understanding of what the htaccess files do - their pitfalls and benefits before messing with these systems.
There's a video "How-To" file as an introduction available so if you're new to this it's a good place to start. There's also lots of information available at the Apache.org website and generally searching for "htaccess security" will show lots more to read. For now, be aware whenever using these files you should be sensitive to the effects on your users and your website.
Set the apache lock to restricted groups on your site, like "Administrator" or your own "special". This means it's only shown to specific members. The content with the directories you choose to protect will be subject to Apache's login system so make sure all data inside these folders is specific and not accessed from elsewhere on your site.
Real Life Example
An organisation uses Joomla! for their website doing what it's good at. This organisation invigilated examinations and require a bespoke piece of software that allows their members to upload files and such. That software has a very basic login so Apache Lock adds more security while easing the administrative burden - their administrative members (Team Leaders) can assign their own htaccess login and individual logins for their Team.
So then, a "Team Member" can access the bespoke software with a higher level of security even though they are not actually members of the organisation at all. This means Apache Lock allows us to extend your security policies to other software easily.
Please note: Free versions of this software may not have all the features described here.
No guarantee is offered or implied. Terms apply.