The easiest way you can apply for the Amex Green card is either online or over the phone at (800) 528-4800. Alternatively, you can respond to a mail offer.
Here's how to apply for the Amex Green card
Online: To apply for the Amex Green card online, click the “Apply Now” button, then enter the requested personal and financial information, review the card's terms, and submit the application.
Phone: To apply over the phone, call American Express at (800) 528-4800. Say “apply” when prompted. Then, you will be connected with an American Express representative who will help you fill out your application.
Respond to a mail offer: To respond to a mail offer, visit the dedicated web page. Another option would be to fill out the application and mail it back in the addressed, postage-paid envelope that came with the offer.
Once you apply for the Amex Green card, you will likely get an instant decision, though it could take a few days or even a few weeks to hear back in some cases. If your application is approved, you should receive your card in the mail within 7 to 10 business days. If you don't hear back right away, you can check your application status online anytime.