placing an image in activity background (with another image)

so I'm working on this app, which basically displays an image and some text. background looks like this http://ift.tt/1Jlq2ml

Now, i have literally set the background of my activity as this image. now i want to implement a function where i can click a button and some stored image would be imported and placed and fit in the WHITE space, and also display some text in the BLACK space.

Any ideas how i would do that ? Thank you :)