Single Contact Sync
From any profile page click the purple "Actions" button and then click "Sync Contact".
This will bring up a modal with a variety of integration vendors that you can sync with, click "AWeber".
This will bring up a list of your AWeber "Lists" for you to choose from. This contact will be added to the list(s) you choose.
An "AWeber" badge will appear near the contact name when the contact has been successfully added to your AWeber list.