Intellij Eclipse and other Installations

I see you are linked to a Java course, where coding occurs in a Treehouse-provided work space or console. Eclipse is a development environment for Android, which is based on Java. But the console is fine for learning Java itself. And quite frankly, if you want to learn Android, it's really best to learn Java first. So you don't need to know about Eclipse to learn Java, which is key to using Eclipse in the first place.

But to go to your question, if you're interested in Android there's a Treehouse course called Android Tools which introduces Android Studio (a development environment based on IntelliJ that replaces Eclipse as the standard), Ginnymotion (a versatile device emulator) and Github (version control, as Ricky explained above). The course explains how to obtain, install and use these tools, and how they can benefit even beginning developers.

I am myself a beginning developer still overwhelmed by all the tools and languages; I imagine I will be overwhelmed for quite some time yet. The beginning Java and Android courses on Treehouse are quite good for people like me with ZERO programming experience. I also found the introductory console and git courses quite useful. In every case, you work with the tools you need to accomplish the task at hand.

To be honest, I wish at this point I could do MORE work in basic Java, on the console, so I can better understand what's happening with Android in Studio.

There's a tremendous amount to learn here. I agree with Ricky -- go slow and just learn to use the tools you need to do what you are trying to do right now, ie, Java. The learning you are doing now in the Treehouse workspace is critical for everything you will do in Android. Learn this stuff well and Android will make much more sense.