Welcome to MR, kawaisoonano
I don't have a Kindle or any experience in formatting, but the below links have information that may help in understanding your Kindle.
Links Every Kindle Owner Should Have
From the MR Wiki...
Kindle Myths and Partial Truths
Amazon Kindle DX
E-book formats
You can even explore using
Calibre and Kovid, the creator, frequents the forums here. We even have a dedicated
Calibre forum.
Did you know that MR has free ebooks? They have been beautifully handcrafted by some very dedicated MR members. (I believe that they are better formatted than Google books.)
For your Kindle..
Mobi / prc format ebooks
download the MobiGuide and get your books via Whispernet..(up on the top left in the blue bar.. click on ebooks.. then in the drop down menu choose Mobipocket download guide)
Free ebook sites
feedbooks.com This site also has a Kindle Guide to download and you can get their books via Whispernet - there is a video on how to use the guide.
manybooks.net
Free and for purchase ebooks
smashwords.com
baen.com
Plus Baen has a
great free library
Have fun exploring the forums and ask if you have any questions.