To retrieve your ‘Seller ID’ and ‘MWS Auth Token’ follow these steps:

1.   Log into  Seller Central using the  Admin (Primary) account
2.  In the upper right-hand corner, click “ SETTINGS
3.  And then select “ USER PERMISSIONS
Picture
4.  You will be redirected to the ‘User Permissions’ page, and from here scroll down to the ‘Third party developer and Apps’ section, and click “ VISIT MANAGE YOUR APPS
Picture
5.  Now, within the ‘Manage your apps’ page, click “ AUTHORIZE NEW DEVELOPER
Picture
6.  From here, enter “ Sellers Arena” as the ‘Developer Name’
7.  For the ‘Developer ID’, Amazon assigns developers unique IDs for each region. Based on the account/marketplace you are currently accessing, enter the corresponding ‘Sellers Arena Developer ID’. NOTE: to add additional marketplaces, you will need to repeat this process.
                a) North America (US/Canada/Mexico): “ 546615959819

8. Click “ NEXT
Picture
9.  You’ll be redirected to a confirmation page where you will “ CHECK THE BOX” to confirm access and click “ NEXT

10.   IMPORTANT: The page will refresh to show your ‘ Seller ID’ and our ‘ MWS Auth Token’.  This is the information we will need. 
Copy these two fields and/or take a screenshot and send them our way!