The iBook author may be downloaded from the Apple store into a Mac computer following the steps below.
1 - Click on the Apple store icon at the bottom of the desktop (dock) of your Mac and type "iBook author" in the search space top right.
2 - Click on the ibook icon (see picture below) which will take you to the iBook author page.
3 - If it is the first that you are downloading the iBook author, then it shows "install" instead of "open" just below the iBook author icon. Click on "install".
4 - Once the download complete, click on the launchpad and you will be directed to the list of all the apps in your Mac as shown below.
5 - Now click on the iBook icon as shown by the circle above to install in at the bottom of the desktop (dock) as shown in the picture below.
The iBook author is ready to use.
More Free Tutorials on iBooks