Received this wonderful gift of a Kindle Fire from my daughter

Find I'm spending much less time on the computer!
Great device.
However, reading things (books) will take some getting use to. I find it tiring to hold it for long periods of time & get quite frustrated having to hold it by the edges...my fingers & thumbs keep slipping onto the screen & making all kinds of things happen that weren't anticipated!! I suppose a cover would possibly help....would be nice with a keyboard also. Must look into that.
In the meantime, glad I found this group. I have much to learn & some of the topics discussed (like book formats, side-slipping (or something like that) will take some research.
I believe the general theme seems to be a lack of books available for download to read on these devices? Is that correct?