htpasswd -c /usr/local/apache/passwd/passwords rbowen
This will create a new username/password file at /usr/local/apache/passwd/passwords with the username rbowen. It will then ask you to enter a password and confirm it.
Do not do this if you already have a password file. The -c option is for creating a new file.
htpasswd /usr/local/apache/passwd/passwords dpitts
This will add the user dpitts to the username/password file at /usr/local/apache/passwd/passwords.