Well, i personally havent tested the html5 engine on Godot recently. But normally you export the files, move the files into your local server's base folder, activate the software you are using for the server( e.g. XAMPP), and then just run the file and it should work.
I always test any html from an outside software that specializes in it, like XAMPP(under windows).
Hope that it helps, good luck!
Edit: btw, in case the above isnt clear, in my xampp install, if i move a folder named "godotexport" (which has the files) to xampp's base folder, i open the browser and go to "localhost/godotexport" and it should 'just work'.
