The eBooks is on sale on the Amazon web site and hence is available for Kindle devices. It is also available as a PDF download which may be purchased from my web site http://www.paulvgibbs.com.
The next step is to make the eBook more widely available through other stores and other formats and to create a forum where purchasers of the book can more easily ask questions and discuss PHP coding issues.
In the mean time you are quite welcome to ask questions via my email.