JavaScript, canvas/whiteboard issues

Hello

My boss would like me to add the attached whiteboard to our course, whereby users click a button, and the whiteboard populates the screen. If I straight up copy and paste the code into a JavaScript trigger onclick, nothing appears to happen. Am I missing something? Or need to remove/add anything?

I'm not that versed on JavaScript and so I'm really not sure why it's not working as expected. Is there any other way I could use the code? The 'canvas' to write/draw on, needs to show up above the course content. It'll be more transparent so that the course content will be visible, and notes can then be added. I'm just really stuck here.

Please help! Thank you in advance.