First you sign up for a project: https://console.firebase.google.com/
You have to do a little set up there. If you use Rex's plugs you will already have seen the process.
There will be a link in the console for both hosting and storage.
Here's the documentation for setting up Node. I think the console also walks you through it.
It's all done via the Node command line. You can even just copy and paste the commands, just ignore the $ part.
The hardest part is finding your home folder. It's something like: C:\Users\yourname\public
You just move your html5 game folder there, and type firebase deploy
Then just go to your root in the console, and add a "/yourfoldername" to the url.