The lesson tool allows you to set up a series of pages that contains content for the student to read and/or questions for the student to answer. The answer to these questions will determine the next page and the content that is displayed. Sometimes it can be used simply to sequence material but the book tool probably serves this type of requirement better if the information is to be presented in a linear format.
With this tool, it is often best to spend a little time planning on paper exactly what you want to achieve using the lesson. Will it be a linear or non-linear experience, will it be graded, can the student only visit the information once, etc.?
This is an advanced tool and you may wish to speak with a member of Learning Technologies (firstname.lastname@example.org) before starting but the very basics are covered in this guide.