Pls help.. Absolute beginners guides

I'm completely out of my depth. It took me a day to install the OS (terrified - not my phone!) and then a week to find and add a licence successfully. Are there any guides for absolute beginners, please? I need to put 1 Android app on this phone, and I don't know how. Where is this Android support or alien wotsit? If there are no guides or they haven't been quite written yet for newbies, I'm happy to add to any rtfm threads. You all don't know what you know! But me and others really do need to know, from the basics onwards. I'm up for changing the world. First though, just how do I add an Android app, please?!