For example...
The canvas is a native HTML-element that can be used to draw and alternate images and render its output to an HTML document. Drawing-methods can be accessed directly through the context of the canvas, however EaselJS will add a layer of abstraction to the canvas by automatically handling all drawing calls so that all you have to do is placing the images and calling stage.update().
"so that all you have to do is >placing< the images"
"that can be used to draw and >alternate< images >and< render its output" (missing comma, run on sentence, alternate is probably the wrong word, I'd use change or replace.)
"The Stage is >so to say< the bottom-most container." That doesn't make any sense to me, I'm Canadian so maybe it is a saying elsewhere but I've never heard "is so to say".
For example, take your home page: "You’re interested in making games or other interactive HTML5 apps, but you don’t quite know were to start and what you will need to accomplish that."
That should be "where", not "were".