This tutorial provides details of setting up a horizontal Constant Contact opt-in form in WordPress with custom input placeholders via jQuery.
Sallie has a good tutorial on Genesis eNews Extended plugin with Constant Contact here. I gave it a try first only to find out that when the Submit button is clicked after a user enters First Name and email, a new tab/window is being opened and that too only with email field pre-filled. Ideally after the form has been submitted, a success message should be shown right there in-place or the user taken to a separate 'Thank you' page.
Step 1
We shall instead use Constant Contact Widget plugin by SourceFound. After activating the plugin, go to its settings and enter your CC username and password.
Step 2
At Appearance > Widgets drag a Constant Contact widget into your widget area (in this example, Home Section 2 of Parallax Pro) and configure it.
Enter the name of list into which opt-in entries should get into in the 'Contact List Name:' field.
If you would like the visitors to be redirected upon the form submission, replace the Success Message with your URL.
Tick 'Ask for first and last name' because we are going to display and use the First name field.
Step 3
Create a file named say constant-contact.js in child theme's images directory having the following:
