Reviewing documentation here is a quick guide that will show you how to use Cloud Storage to host a static website for a domain you own. Client-side technologies like HTML, CSS, and JavaScript can be used in static web pages. They can't have dynamic material like PHP scripts on the server.
Because Cloud Storage does not support custom domains with HTTPS by itself, this tutorial employs Cloud Storage with HTTP(S) Load Balancing to serve content from a custom domain over HTTPS. See the linked troubleshooting article for more ways to serve information from a custom domain over HTTPS. Cloud Storage can also be used to serve custom domain content through HTTP without the need for a load balancer.