There plenty of places to learn about how to write your first e-book. I found at
wikihow.com a pretty good tutorial on how to write your first ebook. Here is a link to the website http://www.wikihow.com/Write-Your-First-eBook . There are also websites that are courses for writing e-books. Here is a link to a website with plenty of videos for learning to write ebooks http://www.lynda.com/eBooks-training-tutorials/1310-0.html . Here is another link to an e-book course with videos https://www.udemy.com/how-to-create-beautiful-e-books-for-free/ . As you can see there are plenty of good free websites on the internet.
Below are a few videos I came across on youtube about ebooks. Of course there are plenty of other videos out there to watch and learn from. All it takes is your time. Who knows this may be your lucky day and make an unbelievable blog.
Intro to How to Make, Market and Sell Ebooks All for Free
What it comes down to is writing an E-Book to place on your blog is whatever you want to do. I myself would recommend that you make the subject of your e book reflect what your blog is about. In other words make it relevant to your blog. Most of all my advise is have fun with it, because that is what makes it worth reading.
Thank You for reading.