So, you've got some custom code that you need to embed into your website? The HTML app is the best way to do it. If you need to embed a Youtube video or Google Map, use the Youtube and Google Map apps, but for any other embeddable code, this is the block for you.
Using the HTML block is dead easy. Simply copy the code you want to embed into your clipboard, and paste in the code by pressing 'control' and 'v' on your keyboard on a Windows machine, or 'Apple and V' on an Apple machine.
If you need to, you can embed html directly into your content app, but this app is cleaner as it will never interfere with your code. Please keep in mind, not all code will work in this app. As we've got no control over what code you paste in here, we can't guarantee it will work. If something's not working, just talk to the organisation that gave you the code.