Editing OpenEMR instance once deployed on AWS

I’ve been messing around with an instance published on template in AWS, but I’d like to customize it similar to what I can do when using XAMPP. In the past, on my XAMPP deployment, I’ve been able to edit and add the patient encounter forms. Any idea how to do that on the Linux machine?
Do I have to make all the changes before deploying the EC2 instance?
Is there something in the template that keeps me from messing with specific forms?

@Peter_Dobbs
I can simply say learn to dockers. The ASW installs a dockers instance. So, to get to the code you will have to get into the container. Learn how to get into the container then you can begin to modify the code.

There are crash courses around the web for dockers and you can search this forum for clues like this one.