Reddit mentions of The Animator's Workbook: Step-By-Step Techniques of Drawn Animation

Honestly, learning the software isn't going to teach you how to animate, you'll just know where the buttons are. I still have a raggedy copy of Preston Blair's book in my book case, which has been around for 40 years.

Another really great book is Tony White's Animator's Workbook. It has practical lessons and some good simple demonstrations of key frames, and exaggerated actions and setting up cycles.

And since you want to learn, you should also get a peg bar, some paper, some pencils, and buy or make a light box.

Now, all of this is if you wish to do animation traditionally on paper, scan the drawings, and finish them in the computer. If you want to draw directly into the software, you'll need to ask someone more knowledgeable than me on which tablet to buy. I understand the Cintique tablets are good, but they are basically a Windows tablet designed for drawing on.

Edit: Cintiq -ue. Told you. Don't know nothing about them.

I learned the basics of animation from Tony White's The Animator's Workbook. It's designed to teach you not only the basics of animation, but how to do it yourself. Of course, since it's from the 80s it also tells you to use film with a camera... a cell phone scanning app is probably easier and cheaper now :) That being said, the basic principles haven't changed, and you can use his guide for filming your animations as a starting point to make your own system. At this point you can probably get it for $5 from Amazon, but if you want it for absolutely free try your library.

Seconding flipbooks though. That's how I got started. They're really fun and easy.

If you want to learn animation, I recommend picking up the Animator's Workbook or The Animator's Survival Kit. I personally bought the Workbook and it helped me a great deal, but I also had the opportunity to thumb through the Survival Kit once. I'm not sure which is actually better.

Worry about this after learning the basics of 2D drawing.