You can work with Mailchimp Groups in the following areas of Chimpegration Classic:
1) Export - You can use this tool to add group information to users in Mailchimp based off of a Query or an Export in the Raiser's Edge. This section of the User Guide will explain more.
2) Remove Subscribers - You can use this tool to remove subscribers from a Group based upon a Raiser's Edge Query. You can learn more about this functionality in this section of the User Guide.
3) Synchronize Constituent Data - Mailchimp Group data can be processed against several areas of the Raiser's Edge including Constituent Code and Constituent Attributes. For more information, please review this section of the User Guide.