XML : Setting background image in android application

For few last days I'm trying to set background image in my android application. First I added my image to res/drawable-hdpi and set it as a background in .xml code of my activity by writing

  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:tools="http://schemas.android.com/tools"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:background="@drawable/bground"      tools:context="patrycja.MainActivity" >    

It didn't work so I tried also to put this image into another drawable folder in res - without success. Then I even changed the extension of my file from .jpg to .png - nothing. So I got into res/values/styles.xml and added this:

   <style name="AppTheme" parent="AppBaseTheme">          <item name="android:background">@drawable/bground</item>   </style>    

Everytime my application compiles but when I try to start it I can't even go to my first activity because it stops. LogCat shows me RuntimeException, InvocationTargetException and OutOfMemoryError. Problem must be here because my app works good with setting colour as a background. Has anybody got an idea how to fix it?