Get Bitnami app to run in the root?

Apologies in advance for the newbie question. I've deployed a small instance running Discourse within the Bitnami console. I can now reach Discourse on the following domain:

http://<myapp>.bitnamiapp.com/discourse

I've also got a CNAME pointing to this server instance. But how can I make the Discourse app run within the root? So it can be accessed directly on:

http://<myapp>.bitnamiapp.com/

Do I need to use Putty to get a terminal window and modify the host headers? Linux is foreign territory for me so any guides to help me achieve this would be much appreciated.