MySQL replication and ProxySQL

I just came across ProxySQL. I have one simple question, if I were to use ProxySQL, do I still need to set up Replication(master-slave) first for MySQL server? Because there is hostgroup(0,1) in ProxySQL which to determine which MySQL server master and slave based on the hostgroups. Or just configure in ProxySQL? Kindly clarify on which steps should I use. Thank you.