Khan Academy ProcessingJS sharing and embedding code in a website

I'm tying to share my game that I made to a website I have, and when I try to the canvas for it is too small and when I tried looking up how to expand this.  The only thing I can find is a post from a year ago where the only answer is to change the size of the iframe, which I've tried doing for the past few hours and still have no idea what to do.  All I need to do is change the size of the window that the game is in to be 500x600 pixels.  Can anyone help me?