Here is some info from the web
on using the Kindle app.
To download titles your device must be connected to a wireless or data network, but you do not need to connect your device to a wireless or data network to view titles that you have already downloaded.
View all content in your Kindle library:
Tap the Menu 
icon and then tap All Items.
Switch between content stored in the cloud and on the device:
While in a content library, tap the Cloud and Device option at the bottom of the screen.
Check for recent content:
Tap the Menu icon and then tap Sync.
Remove content from your device:
While in a content library, press and hold an item, and then select the Remove from Device option. This does NOT delete the document from your account – it can be downloaded again later.
Sort content on your home screen:
- Sort by content type:
Tap the Menu icon to sort content by All Items, Books, Newsstand, Docs, or Collections. - Filter by title, author, or recent:
Tap the Sort
icon to sort titles by Recent, Title, or Author.
Change the display of your content:
- Display title covers in a grid: Tap the Grid
icon. - Display the title covers in a list: Tap the List
icon.
CLICK HERE to learn more, including how to
- change font/size/etc.
- Add bookmarks
- Change locations in the book
- Explore the book with X-ray [may not work with all documents]
- Add highlights
- Add notes
- Look up words in a dictionary