Welcome Tabitha (sounds better than tabbi which sounds like a cat
) I have two 505s and love them.
As far as what to read, there are ton of free and well-formatted books in the library here. Also free books at books.google.com and at feedbooks. Many other places to purchase books and be sure and check your local library and see if they have electronic check outs mine does here in Denver and it's great! Check the Wiki for places to get books:
https://wiki.mobileread.com/wiki/Main_Page
Enjoy!