This is really easy, just choose an app that suits you, I would recommend habboelectron (just Google it and click on the GitHub link). Then follow the little instructions on the page and everything should work great.
I would just follow this guide (Click here) step by step and if you are unsure what kind of VPS you want to buy, I would recommend the Cloud VPS M package from Contabo, although the smaller one should be enough if you just want to play with your friends.