Htpasswd is a tool used to manipulate flat files containing usernames and passwords for basic authentication of HTTP. In Cent OS htpasswd is part of httpd-tools pack. In order to install it, you must enter (root access required):

yum install httpd-tools

After entering the command you will see a result similar to the one shown below:

htpasswd install completion

To verify that htpasswd is installed you can enter the following command:

htpasswd -h

If everything is OK you will see help of the command:

Help of htpasswd after completion of the installation