I want to create multiple usernames/passwords for a certain directory, how do I do this?

There is a tool that allows you to set password protection for a specific folder. Just go to the Advanced > Admin tools > Password Protection section of the Web Hosting Control Panel.

Here enter the username and the corresponding login password.  Click on the “New Password Protected Area”. Then, select your domain from “Hostname” or browse to the full path to the protected folder in the “Path” field (e.g. /www/my-best-domain.com/protected_folder). If you need to set more users, repeat the above steps, just use different usernames.

IMPORTANT: If there is an .htaceess file within the protected folder, the protection would not work, so either remove it or consider another password protection technique.