To add or change your billing contact for your subscription purchases with Open Door via https://shop.opendoorerp.com:


Login in to your account and select "My Account"


Scroll to the bottom and select to Update Billing Contact and follow the instructions.




Are you not a current customer and want to order online?  Register for your account.  Additional help can be found via 

https://support.opendoorerp.com/solution/articles/17000064049-how-to-shop-open-door-for-microsoft-office-365-dynamics-365-and-azure