How do I deploy a node app on Google Compute Engine?

I followed these steps: https://developers.google.com/deployment-manager/nodejs

But I don't really know where to go from there...how do I actually deploy my node application? Where is the node code? It's not on my machine, I don't think. So, how do I edit it?

I tried connecting to the shell, installing a node app with yo, and serving it to port 9000 with grunt, and then allowing that port with

gcutil --project <project-id> addfirewall http9000 --allowed tcp:9000

and navigating to the address, but it didn't work. However, navigating to 8080, which is what the tutorial said to do gets me Hello World, but I don't know where that code is. Thanks in advance.