You have to implement a canvas that allows the user to draw on it and then set the background of that canvas to that particular image. This is just a guess but its somewhere there abouts.

for more information you can check this .
http://www.ixtendo.com/how-to-add-a-caption-text-over-an-image-in-android/
https://stackoverflow.com/questions/6159186/how-do-i-write-text-over-a-picture-in-android-and-save-it
Hope it may help full to you.

You have to implement a canvas that allows the user to draw on it and then set the background of that canvas to that particular image. This is just a guess but its somewhere there abouts.