Wordpress->Gravity Forms Integration (via Zapier)
1. Install the Gravity Forms plugin in your Wordpress account
Go to your Wordpress plugins page to install the Gravity Forms plugin. Then be sure to install the Zapier Add-On by going to the Forms->Settings section.
2. Create a Gravity Forms form
They have good documentation on how to create a form.
3. Sign Up for Zapier
Go to www.zapier.com and signup for an account.
4. Request the StreamSend action to be added
Click here to Add the StreamSend action to Zapier. You'll need to be logged into you Zapier account to get the action added.
5. Create a Zap (Gravity Forms to StreamSend)
Select the Trigger and Action
Select Gravity Forms->"New form Submission" as the Trigger and StreamSend->"Add Subscriber" as the Action.
Connect Gravity Forms
You'll be asked to link your Zap to Gravity Forms. Go to Forms in Wordpress, then go to Settings->Zapier under the form you'd like to sync up. You can then copy and paste the link that Zapier provides as the feed into the form. 
Connect StreamSend
For StreamSend: The API login ID can be accessed from the account link in the upper right hand corner. The key will need to be pulled from your existing code or you will need to generate a new one from here. If you have not activated you API access yet, you will see a link here to do so and it will provide you with your credentials.Configure StreamSend
Refer to our Configuring the StreamSend Zap article for detailed instructions on how to configure StreamSend options in Zapier.Test Your Zap
Under the Test this Zap section in Zapier you can do a test submission to make sure the integration is working properly.
Turn your Zap on
Click on the "Turn Zap On" button to turn your Zap on.