Here's an excellent selection of tarot books to help you understand tarot. Many of these books come complete with a deck of cards and this is a good way to get started. There are a lot of e-books available on the subject but to be honest I would start with a good hard copy of something that's easy to understand. The original Rider Waite text, for example, is quite a difficult read and isn't really recommended for a beginner. It's far better to start with something simple and work your way up. The Tarot Bible has been recommended by several students and if you can find this tarot book in the ebay auctions it will be well worth the money.
Pickabook also has an excellent choice of tarot books at competitive prices. A good selection is shown below but you can find hundreds of bargain tarot books if you go to their website.
More tarot books can be found on ebay and some of the auctions are shown below.