Some blocks don't have "help" functions

Ok

Thank you!

Thank you!

Should I only include how to switch to scenes and show which chapter you can get more information from?

I would say briefly what a scene is, i.e., "A scene is a project included along with others in a super-project." Then show the simple version of the block and say that the dropdown lists the available scenes. And then say that clicking the arrowhead at the end once or twice gives the long versions, and the second input is a message as in BROADCAST, and the third input is a text or numeric value to pass along with the message.

If you're ambitious and there's room, you can show what the value of MESSAGE will be in the WHEN I RECEIVE block in the new scene, if there's a datum as well as a message.