I have written the synopsis in the appropriate box but am unsure as to what to write in these boxes…
For the author comment I would suggest writing your take on the book, why you wrote it or who you think should read it. It is a bit of extra information so people have an idea about you and why you wrote the book.
The blurb addition is something added to the blurb when sent to distributors. So for example you might mention that you can find out more about the book at a certain URL. It was a requested feature from a year or so back but it gets so little use I might depreciate it pretty soon.
Thanks for the questions, anything else I can help with please let me know!