Use timer to move a canvas or graphic

Good night, I need help creating a timer, to work like this:
When you click start button, it starts time on a canvas and moves it up or down at a constant speed.
And stop the movement by clicking stop.
I'm new to programming, but I would like to create this timer event to develop into a game, or graphics.

Welcome Jose.

You might use the example Creating Animated Apps

or do one of the tutorials at http://appinventor.mit.edu/explore/ai2/tutorials Several show how to use the Canvas, ImageSprites and a Clock together.