Here is a simplified description on how to create an htaccess / htpasswd file :
To protect your admin area you can create an htaccess / htpasswd file.
(1) Create an .htaccess file
In the first box enter some optional text which gets displayed in the login box
In the second box you need to enter the file path name to a second file htpasswd file. The htpasswd file is where the list of users / passwords are to be located.
Click on the button, copy the text and place it into a text file. Name this file .htaccess and upload it to the folder that you want to protect. In this case this would be the /admin/ folder.
(2) Create the .htpasswd username / password file
In the first box enter the username.
In the second box enter the password.
Click the button, copy the text and place it into a text file. Name this file .htpasswd and upload it to a suitable location on your server. This can be anywhere on your server, but usually in a defined folder. The location is the same location as was entered in (1) above.
The folder as defined in (1) should now be protected by the username / password as defined in (2)