Add field in contact to display current marketing group/email list membership

Add field in contact to display current marketing group/email list membership

Hi all,

I am trying to add a field to the contact view page that shows the membership of a marketing email list from our 'Marketing' tab in Zoho CRM. I would like to also be able to add a contact to that list (or multiple lists) from the contact view page.

Can anyone help? I can add the custom field but cannot see how to map that field to pull/push data to/from the marketing list.

Cheers! 
Alex