Welcome to MR, Xanthe, and congratulations on your Aluratek Libre!
You may already know about the beautifully hand crafted ebooks by some very dedicated MR members, but just in case, check out the
Mobi / prc format and the
ePub format books for your Libre.
Just in case.... an awesome Sci Fi site to check out. No DRM and a great free library.
http://www.baen.com/
I see you have already jumped right in, so enjoy the threads and just ask if you have any questions.