learn-rails | example Rails 5.1 app | Learning library

I have just completed the detailed and well-explained Rails tutorial by Daniel Kehoe and am at the end trying to experiment with Rails Composer. I am having a problem creating the app on both Cloud 9 and Windows 10 with the same error. The app creates but only a basic rails app and not the Rails composer app with all the extra features.

First I tried to create the new project with the following command:

I am trying to set up the configuration in preparation for following Daniel Kehoe's learn-rails tutorial book, but I am having trouble setting up the environment variables. The book seems to explain how to do it on Mac and Atom but not with cloud9. I am supposed to put the environment variables into a file called ".bashrc" but I don't know where to find this file as it is hidden.

When trying to add a new GitHub repository to my project, I am getting

fatal: remote origin already exists.

Then, when I try to do

Currently taking the intro to ROR on CodeAcademy, and the flow so far:

1. Create ROR App,
2. Modify Controller by creating a method inside the PagesCotnroller class.
3. Modify the Routes to point the 'welcome' request to 'pages#home' controller/method.
4. (Here's where I get confused, they say: Ok, now it's time to mod the View (home.html.erb)... find it in folder x/y/z. But where in this flow does this project specifically chose the home.html.erb file vs. another view. Granted for this test project there is no other view file in the folder, but what if there were 20 of them? I see steps 2 and three connected in the code, what about 4?

This may seem like a rudimentary question, but I rather understand now then move forward without having a clear core foundation.

Course link: https://www.codecademy.com/courses/learn-rails/