This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
If you have your image resource in drawable folder you can refer them as follows:
If you bundle them in assets, then you will have to read these files as streams using AssetManager and then create a Bitmap from these stream using BitmapFactory. After this is done, you can set this Bitmap as background property of your View or ViewGroup in code.
Putting an image resource in drawable folder is NOT JUST copying an image file to a folder in the Project's structure.(Read official documentation on Application Resources). Android tools(aapt et al.) do a lot of stuff behind the scenes.