@Peter Daniels Deploying a project from VS does not really change even if you are using WebSockets. The quickstart doc should help you deploy the application and App Service "runs" the application for you.
As for WebSockets support, make sure you enable the setting in the configuration blade. And the URL itself would not be any different from what you would use for local development, apart from the domain.
That being said, like Lex mentioned in his comment, you might want to consider Azure Web PubSub which is a service that is designed for WebSockets Hosting at scale.