how can I change my credit card information to download free apps

Why? You can download free apps. They are not charged to your credit card.

If you want to be able to have an account without a credit card, then you must create a new account:

Creating an iTunes Store, App Store, iBooks Store and Mac App Store account without a credit card

If you are asking how to remove the credit card go to Settings>iTunes & App Stores>Apple ID. Tap your ID. Tap View Apple ID. Enter your password. Go to Payment Information and select "None", if the option is available, if the option is not available for you, then you will have to create a new Apple ID using the instructions in the link that Kappy posted above.

You must follow those instructions exactly - step by step, you must not be signed into another Apple ID when you create a new ID and you must have another valid email address if you already associated an email address to another ID.

I can not create a new account cause I'm at my limit trying to figure all this crap out before. So now I'm stuck and cannot figure it out and I can not download free apps or update any of my apps.

All the accounts have to sink together. Too confusing and now I'm stuck. How do I solve this problem. I've tried everything else recommended. I cannot figure it out.

Very upset apple customer...

<Edited By Host>

How to Get Apps From the App Store Without a Credit Card

http://ipadhelp.com/ipad-help/how-to-get-free-apps-from-the-app-store-without-a- credit-card/

Creating an iTunes Store, App Store, iBookstore, and Mac App Store account without a credit card

http://support.apple.com/kb/ht2534

If None is not available - On your computer launch iTunes and click "iTunes Store" in the left navigation pane. Click the "down arrow" next to your name at the top right side of the page and click "Account." Enter your username and password and click "View Account" to log into your account information. Next to your Payment Type, click "Edit." Select the "None" button and click "Done." Confirm that your card has been removed by returning to the Apple account information screen. Under Payment Type, it should say that there is no credit card on file.

 Cheers, Tom 😉