SSH remote access,permissions issue

My friend has installed 4 nodes at his server in Norway.I wanted to add new nodes to cluster.I have logged in with ssh and password.ssh pi3@84.208.89.002 -p 22022 Last login: Wed Feb  7 06:59:05 2018 from 94.189.152.722 Later sudo su,and have repeated 100% exactly the same operations as he did.

How to start cluster after the yaml file has been changed?

I have changed yaml config file.Now I want to start my cassandra cluster.I have restarted node cassandra.service - LSB: distributed storage system for structured data   Loaded: loaded (/etc/init.d/cassandra; bad; vendor preset: enabled)   Active: active (running) since ma. 2018-02-05 09:27:05 CE