When you click on this help button, the library is displayed:
The books on the shelf are separate sprites. When you click on any book, a paragraph of information will appear in a another sprite. This content sprite has a different costume for each book and simply changes costume when a different book is clicked:
The code for each book is as follows:
Remember, the book sprite cannot change the costume of the content sprite and has to broadcast a message so that the content sprite can respond by switching costumes.
The code for the content sprite is as follows: