Vision Helpdesk License is based on domain name. While purchase if you have choose License Domain as : yourdomain.com that means you can install Vision Helpdesk on any folder under your domain -- example: http://yourdomain.com/support/
Unzip Vision Helpdesk setup zip and upload the files under upload folder to your servers support folder and in browser open setup url example : http://yourdomain.com/support/setup/
Make sure you have 777 permission set for config.php and 755 for console/pipe.php (pipe.php is required in case of email piping)
Create database on your server
On setup page enter your database details and admin details and run the setup.
If your setup is complete without any errors you can delete setup folder from your server.
Once you have complete setup you can go to manage portal http://yourdomain.com/support/manage/ This is where admin and staff will login. Client portal will be http://yourdomain.com/support/