how to configure neo4j database on ec2

I set up a neo4j database on ec2 and am not sure how to access it with my restclient. Firstly, how do I change the username and password once its on ec2 and running? Also, what do I change my localhost to so I can access the server?

This is the example statement I want to know how to configure:

from neo4jrestclient import client
db = client.GraphDatabase("http://localhost:7474", username="neo4j", password="neo4j")