Congratulations, someone downloaded your eBook. This introduction is your chance to make sure that they actually read the book from cover to cover.
Reading an entire book can seem like a big task. This introduction gives you a chance to convince your reader that they will miss out if they do not take the time to read the complete book.
Your introduction should be no more than one page long so that a busy person can scan read and still get a good idea of the overall message.