If you want to put Constant Contact on your landing pages you have three options:
1. Get the form from Constant Contact
Embed a form from Constant Contact
2. Set Email Management to Custom. Selecting Custom for your Email Management
3. Put your the Custom Email Form shortcode, , in the Content Area where you want to display the form. The Custom Email Shortcode will be where your email form appears.
4. Paste your email form code in the Custom Email Form for Shortcode box. You get this from Constant Contact.
5. Save and the view to see your form.
Here is a tutorial that shows you how to use the share method, http://www.constantcontact.com/display_media.jsp?id=563t
Third party services