I am looking at the Fire HD 8 Tablet for my wife. Does it need to use the internet to read the books with the fire HD 8?

Hi, luckly I find something useful. Look closely to what the person of the video is doing, and then, the only thing you need to do is push the Micro SD card, with your nail, softly.
Amazon Fire HD 8 Tablet

Have you tried going to settings and checking for an update?

Yes, Kindle is a name used for all the Amazon tablets and e-readers.

Kindle 2, 4, 5, 7, 8
Kindle DX
Kindle Touch
Kindle paperwhite (1,2,3 generation)
Kindle Voyage
Kindle Oasis
Kindle FIre 7
Kindle Fire HD 6, 7, 8, 8.9, 10
Kindle Fire HDX 7, 8.9

And I probably missed some in here.

Amazon Fire HD 10 Manuals
Amazon KINDLE 1ST GENERATION Manuals

Check the Serial Number You can find this sixteen digit code in the box your Kindle came in or when you click on Settings and go to Device Info. Find your specific generation or type based on the first four characters. Kindle 2: B002, B003 Kindle DX: B004, B005, B009 Kindle 4: B00E, B023, 9023 Kindle 5: B012 Kindle Keyboard: B006, B008, B00A Kindle Paperwhite (2012): B024, B01B, B01C, B01D, B01F Kindle Paperwhite (2013): B0D4 or 90D4 Kindle Touch: B00F, B010, B011 Kindle Fire (2011): D01E Kindle Fire (2012): D026 Kindle Fire HD 7(2012): D025 and D059 Kindle Fire HD 7(2013): 00D3 and 00D2 Kindle Fire HD 8.9: B0C9, B0CA, B0CB, and B0CC Kindle Fire HDX 7: D0FB, 00FB, 00FC, 0072, 00FD, 00FE, 0073, 006C, 006D, 006E Kindle Fire HDX 8.9: 0018, 0057, 005E, 00F3, 0019, 0058, 007D, 007E, 007F - See more at: http://glyde.com/glydecast/how-to/which-kindle-do-you-have/#sthash.bAbYPdzQ.dpuf

To remove a book or magazine from your Kindle Fire HD libraries, follow these steps:

1. On the Home screen, tap Books or Newsstand to display your library.
2. Locate and press your finger on the item you want to remove. A menu appears.
3. Tap Remove from Device press the helpful button

How to delete books from Kindle Fire HD
How to Delete from Kindle Fire
How to Delete Books and Docs From Kindle Fire HD8 HD10

Amazon.com: Customer Discussions: Font size changing on Kindle Fire HD

www.amazon.com/forum/kindle?_...1...

Amazon.com, Inc.Dec 6, 2012 - The best Kindle would be the Kindle Fire HDX 8.9 - it has the largest screen and the .... before purchase... does the Kindle Fire 10" have an option for large font? Increasing font size on Kindle ...
Nov 28, 2011
change font size on Kindle Fire
Nov 1, 2011
More results from www.amazon.com

Hook your kindle fire to your computer. When the auto play window appears click on "view files". When your kindle hard drive files appear then look for the books file on your kindle. Click on the books folder then copy and paste them on your desktop then unplug your kindle. Plug your wife's kindle in then do the same to open her books folder then copy and paste the books from your desktop into her book folder.

Sounds like your wife's kindle is registered in your name. You can find out by logging into your account on amazon. Up the top open your account window then scroll down and click on " Manage Your Devices". If your wife's kindle in on your account then you have to unregistered it from your account then see would register it in her name. She can do this while on her kindle table.