Remote desktop connection from windows to AWS ubuntu via AWS redhat

I would like from my windows to access my ubuntu in AWS VPC.

Currently, I can do it via SSH. I open putty, connect to my Redhat, and from this server, I can start another ssh to connect to my ubuntu.

The firewall connection are done so I can only connect to Redhat from my company network, and I can only connect to ubuntu from redhat.

What I would like to do now, is to connect with desktop environment instead of SSH command line interface. I followed these steps, http://ift.tt/1O71n7q

But then, I block a little bit. First, I am not really sure I should use public ip or public dns of ubuntu. I should probably set a ssh tunnel via putty, and then a ssh tunnel on my redhat, and then connect on localhost with a port redirection... is it the right way to do this ? I was thinking using the cmd C:\WINDOWS\system32\mstsc.exe /v localhost:33389

(33389 is just random here) I dont know much about port, so which one should I chose ? what do I have to do check to find the good one ?

Thanks for your help.