[BlueOnyx:23779] Docker on 5209R

[Colin Jack]

This is a very NOOB question and probably one for Dirk Estenfeld to answer easily.
I have never used docker before!

I have installed docker on a 5209R VPS and it is running okay.
Downloaded a docker image for Nagios and created a new container.
Fired up the new container and it says it is running on TCP 9090

I assumed that I could access it via http://<VPS IP:9090 but that doesn't work.
Where am I getting this wrong?

Also, how do I get to the folders to configure it?

 I am clueless on this so would appreciate some basic guidance to get going!

Many thanks

Colin