Here you will find a compilation of our learning resources, external to the documentation. If you just want to see the documentation, you can start from here - Quick start
HTML offers a great variety of workflows that you can use in order to create the content for your game. You can use visual WYSIWYG editors such as Coherent Editor and Google Web Designer or use standard web development approaches and benefit from popular UI frameworks and libraries such as Bootstrap, React.js, Knockout.js and others. Choose the workflow that best fits your team's profile. Below you can find several content creation tutorials to get you started.