Android Studio Random.org

I'm new to APIs and Libraries and I want to know how I can implement Random.org into my app. I need a random number from 1 to 6 (I'm making a dice app) and I only need one number to be generated. I've got my API key, bu I don't know what to do next. Random.org itself isn't all that clear on what to do next exactly. Does anyone of you know the exact steps to make a TextView which generates a new number at the press of a button?