HTMLShield is a user-friendly piece of software offering a first level of protection for your local or online webpages (for the latter, it can easily replace an .htaccess which is more secure but harder to implement). To encrypt your HTML file, drag-and-drop it on the program, or directly launch the program then select it in the opening window, you will then be proposed to type your password. The same manipulation on a file which is already encrypted will ask you to remove the password protection (back to a non-protected file).