By default, MongoDB does not have a user or password set. It is secured by restricting access to the local loopback interface. There are a number of different ways that you can set up authentication. The MongoDB security checklist is a good starting point for the options available. This tutorial covers some basics about DigitalOcean's MongoDB One-Click including opening it up for external access:
The default database name is simply test If you enter the MongoDB shell by running the mongo command, typing db will return the name of the database. use can be used to switch databases. If the database didn't exist yet, it will be created. For instance,
> db
test
> use new-database
switched to db new-database
> db
new-database
