I just got a kindle for Christmas. It's the kindle fire, not the original, but I'm sure they could be close to the same thing.

To get wifi, there should be a little settings button by the battery (it sorta looks like a screw.) If you click that, you should see the option for volume, brightness, wifi, etc. Click wifi, and you'll get the options of different network connections. Just click yours, put in the password for you wireless Internet, and viola! You have wifi. My aunt has also told me about the free books, but I have yet to find them.. Sorry, if I do I will let you know!

As to change credit card information, go onto amazon and log into your account. I'm not sure how to change it unless you buy something, but I'd you purchase something off amazon, you are able to change address, credit card info, etc. Then you have the option to make this the default payment option.

I hope this helps! Good luck with your kindle, it's a lot of fun. I love it!