1. Install “MailChimp for WordPress” Plugin and activate. 2. Add API Key here ( Dashboard >> MailChimp for WP >> MailChimp ) How to get API key: http://kb.mailchimp.com/integrations/api-integrations/about-api-keys 3. Visit MailChimp for WP >> Forms You can see your forms. Check a list which you want to add. and click “Add new form” ..