I have written few tutorials to teach HTML5 game development to the beginners. I hope you would find them useful if you are looking for how to begin with HTML5.
Tutorial Part 1: Snake game using HTML5 and KineticJS
Tutorial Part 2: Snake game using HTML5 and KineticJS
Collision Detection using Bounding Box method in HTML5 and KineticJS
Sprite Animation in HTML5 and KineticJS