To create a error page for your domain select the Free Shared Hosting service in your personal cabinet (https://my.llhost-inc.eu/clientarea.php) and click on "ISP Manager" which will take you to your domain control panel:
Personal cabinet > Services > Select "Free Shared Hosting" service > "ISP Manager" button.
Select "WWW-domains" in the WWW section of the domain control panel and then click on the "Error pages" button at the top:
Click the "Add" button and select the page you want:
After clicking the "Ok" button you will be taken back to the list of error pages you created: