Procédure
Sub-domains are very useful for dividing a site into several distinct parts, each with a clearly defined address. They also avoid having to use file names that are too long.
1. Connect to Plesk and click on Add a Subdomain
2. Add a Name to your sub-domain and indicate the Document Root (Path to the site directory) and click on Ok to validate.
To find out more about the plesk panel you can consult the official resources:
Ask the LWS team and the community. Answers are published after moderation.