Hack School Server

Hello there I require some assistance. I want to hack my school server. Before you shoot me down as a lvl 1 newb, I would like you to know that I am a lvl 1.5 newb.

I have become an administrator on the local pc (local domain) through a kali live cd, but I want to become an administrator on the global domain so that I may troll my friends through remote desktop connection and shit.

I think I need physical access or something of the sorts. Perhaps a man in the middle attack ?

Any and all help is appreciated. You do not want to be spoon feeding nor will I learn being spoon fed and thus require just a nudge in the right direction. My interests are not malicious and if any additional information is required do ask. Thank you for taking your time to read this and thank you in advance for your help