Install instructions for Ubuntu 15.10

I’m sorry to say that as a newcomer to Linux I’m not able to install the latest version of Root at Ubuntu 15.10. Can anyone please give me a step by step instruction on how to install it to get it fully functional? It would be much appreciated.

The instructions are explained in this post:

You have maybe to replace the version numbers appearing in that instructions, eg. 4.8 with 4.9 or sth similar, check your package manager.

Thank you, much appreciated!