Creating children is similar to creating new znodes. The only difference is that the path of the child znode will have the parent path as well.
create /parent/path/subnode/path /data
create /FirstZnode/Child1 firstchildren
[zk: localhost:2181(CONNECTED) 16] create /FirstZnode/Child1 “firstchildren”
[zk: localhost:2181(CONNECTED) 17] create /FirstZnode/Child2 “secondchildren”