1.    Login to your Plesk Control Panel

2.    Navigate to Websites & Domains.

3.    Click Password-Protected Directories.

4.    Click Add Protected Directory.

5.    For the Directory name, specify the directory that wants to be password protected. For

Title of the protected area, enter a title as a label of the directory. After done, click OK.

6.    Navigate back to Password-Protected Directory. Click on the directory that you created earlier. 

7.    Click Add a User icon under Tools.

8.    Fill in the Username, Password and Confirm Password field. Once done, click OK.