iPad Cocos2d drawing app

I am developing a Book App for children. I am using the Cocos2d framework. I have pages set up, where the child can swipe through and different animations and interactions happen. However, one one page I need for the child to be able to move a pencil graphic around, and it will draw on the white background. (So in other words, the move the pencil and the lines are drawn from the tip of the pencil.) I also want the child to be able to use an eraser graphic, swipe it over the lines and the lines will disappear. And they should be able to save the picture to their photo album or send it (maybe via email or Facebook). I need someone to be able to make this work in my existing project, then be able to explain the code to me so that I can duplicate it on other pages. thanks for your time!