In order for a contact to be added to your account, they need to be subscribed to at least one contact list. In the example below, the contact would be added list id 1, which is the 'General Interest' list by default.
You can get a full listing of all the contact lists in your account by doing the following:
I hope this helps. Please let us know if you have any questions regarding this.
If you are looking to add a contact to a list that already exists in your account called "CRM Data" you would want to reference the list using the id as shown above. Unfortunately we are not able to query our API by the name of the list at this time, so the list Id is the only way this can be done.
If however, you are looking to create a new list in your account, you would want to use code like the following:
We are looking to overhaul our C#.NET Library in the near future, and specifically around the functionality to do with creating Contact lists, and adding a contact to a specific list.