Step 1 - Click "settings" from the avatar dropdown at the top right corner of the screen, then click "Newsletters" from the right hand panel. Click "Connect Mailchimp"
Don't have a MailChimp account yet? Go to https://mailchimp.com/ to sign up.
Step 2 - Log in with your Mailchimp user credentials, then select the email list you want newsletter subscribers to be added to.
How to Disconnect the Mailchimp Account
Once connected, the email list name will appear under the "Connect Mailchimp" button. Click the trash icon to disconnect the account.