If you have a dedicated or virtual private server, it certainly is possible to install ISPConfig on them. It's your option to install what ever control panel you want on YOUR server. You just have to know how to use Putty or what ever SSH client you use.
You last post doesn't make any sense. Do yo mean you don't know how to configure your domain from your domain registrar? In that case contact your registrar and have them configure it for you. They need you to stay with them and most likely help you input the proper settings.
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