How to work with AJAX and WordPress?

You’re not using wordpress default ajax mechanism.

To do that:

jQuery.ajax({
  type: "POST",
  url: "/wp-admin/admin-ajax.php", // Send request to admin-ajax.php
  data: newcontact, // Can be anything. As per your need
  action: 'myaction', // Required to send otherwise WordPress AJAX won't authorize your request.
  success: function(data) {
    jQuery(".follow-user").html(data);
  }
});

AJAX Request Handler

add_action( 'wp_ajax_myaction', 'so_wp_ajax_function' );
add_action( 'wp_ajax_nopriv_myaction' 'so_wp_ajax_function' );
function so_wp_ajax_function(){
  //DO whatever you want with data posted
  //To send back a response you have to echo the result!
  echo $_POST['name'];
  echo $_POST['age'];
  wp_die(); // ajax call must die to avoid trailing 0 in your response
}

You can Refer WordPress Codex. http://codex.wordpress.org/AJAX_in_Plugins. It’s pretty well documented.

Here’s already answer question to your problem. i.e. https://stackoverflow.com/questions/17855846/using-ajax-in-a-wordpress-plugin