You should start with studying the 2D graphics capabilities of the Android library. Here's another good reference article. It lists some drawing options including drawing to the Canvas object which is probably the right choice for the kind of game you're describing.
Here's a full but simple example of handling the onDraw event for a canvas and performing custom drawing. Here's a small bit of the code:
paint.setColor(Color.BLUE);
canvas.drawCircle(20, 20, 15, paint);
The above is a simple example that draws a circle with a particular size to a particular location on the canvas. It's a good place to start. To finish your game you'll be drawing bitmaps which is a more complex process but conceptually similar.
