Login to admin of the particular site where you wan to connect the contact form with Constant Contact.
Follow the steps,
1. Forms -> Constant Contact -> Add New
2. From the Constant Contact form, Select Constant Contact List. Here you can decide which contact list you want to add them, Eg: ePray! Global
3. Select Gravity Form Eg: ePray Newsletter SignUp
4. Set map fields, Set Gravity Form fields data to Constant Contact Fields.
Now you can find ePray subscribers list from Constant Contact List “ePray! Global”.