You have good timing. I have an Amazon Visa card and I usually pick Starbucks gift cards as my rewards for accumulated points. Your question came in a few days before I was due for another card to arrive, so I waited and can show you step-by-step exactly how to add a new Starbucks card to your Starbucks Mobile Card app.

Before we start, though, it's important that you ensure you have the right application on your phone as there are two: The myStarbucks app [iTunes link] offers an easy way for you to remember your favorite drinks and find the closest Starbucks, while the Starbucks Card Mobile app [iTunes link] actually lets you store your cards and use the iPhone to pay for transactions at Starbucks locations with the correct type of scanner.

Got the right one? Good.

Here's the card I got, yours probably looks the same:

The key information is on the back of the card, both the number that's visible and the number hidden underneath the "scratch off" security bar:

If for any reason that scratch off silver metallic portion is already exposed (it's an 8-digit number) then your card is probably compromised or even used up. I'd immediately take it back and ask for another one. Good luck, that's a tough call for a retailer since there's no way to know whether you're just pulling a fast one or not. Best to learn to check those before you purchase the card in the first place.

Anyway, grab your iPhone (I have an iPhone 4, but it should all look the same) and find your Starbucks Card Mobile app:

In the above, it's the app on the right. The "Starbucks" app doesn't work with cards, as discussed earlier. Launch it and you should have a security code set up for the app (since it's a pay-by-scanning app that lets you reload off your credit card with a few taps, it'd be a disaster if someone else got ahold of it!), so you'll see this:

Enter your code correct and it'll show you the active card and its running balance:

To pay for something, just tap on the "Touch to Pay" button and show it to your friendly Starbucks barista. We want to add a new card, however, so instead, tap on the "Add New" button I've highlighted on the top right.

Now you'll see it prompts you for both the card number and the secret code that you should now reveal by scratching the silver bar off the back of the physical card with a coin, fingernail, knife, machete, whatever.

When you've entered the correct number of digits, the "Add" button on the top right will become active and you should then tap on it...

Since you already have the Starbucks Card Mobile set up, you've already tied it into an account at starbucks.com/card but if this is your first card, you'll need to go to their Web site and tie things together. It's pretty easy...

Make sure that the account name is correct (I"ve blurred mine out for privacy), enter your correct password, tap on "Sign In" and it'll transmit the new card info to the Starbucks servers:

After a few seconds, if the numbers are valid and entered correctly, you should see the new card appear with its current balance:

Nice. How they know what style or design of gift card you have is a bit of a mystery, but they have a lot of digits to play with, so perhaps it's the last four digits and each card design is assigned a unique code. In any case, there you have it. Ready to go. And if you want to switch back to your old card, no worries, just tap on "View All" on the top right and pick your main card instead.

Now that I've shown you how to do that, don't forget that you can thank me by buying me a latte or chai directly. Check it out: Buy Dave a Cuppa. :-)