This help note is shown because this note of type Render HTML doesn't have required relation to function properly.

Render HTML note type is used for scripting. In short, you have a HTML code note (optionally with some JavaScript) and this note will render it. To make it work, you need to define a relation (in Attributes dialog) called "renderNote" pointing to the HTML note to render. Once that's defined you can click on the "play" button to render.