title: adding image resources and using one as a layout background
body: <p>so im working on my first app and i have a question about images</p>
  
  <p>first off, theres 4 different drawable folders, do i just drop an image into one of them? what is the proper way of adding a resource image?</p>
  
  <p>secondly, i know theres a bunch of different resolutions for phones. should i just use one that is say, 960x720dp? or is there another appropriate way of doing this? i want to add an image as a resource into my project, then use it as the background for my app layout...</p>