Saving images in a folder on an Android actually is a very good idea. However, AI2 does not have a save/retrieve file function yet, so doing what you want to do is not easy. There a complicated ways to save folders or to view images. This assumes you save images as Resources. Do you know how to do that?
http://puravidaapps.com/snippets1.php#canvas
However, to do that, you have to load the images at design time.
It is possible to save images created with Canvas internally in the app. You do that using a TnyDB. Do you know how to use a TinyDB.
If you can not answer both questions with a yes, you should do more tutorials to learn the programming techniques. Try here:
Regards,
Steve