Integrate Below Api Code With Mve 4.2.x

Store Builder Questions
1

Hi How can we integrate the code below to pass the email id etc when a user creates an order or registers on the site?

http://stackoverflow.com/questions/37035541/php-how-to-subscribe-user-to-mailerlite-using-api

2

Use the place_order hook (app/functions/fn.catalog.php)

3

Use the place_order hook (app/functions/fn.catalog.php)

Cant find this hook ?

4

Cant find this hook ?

Sorry, correct file is app/functions/fn.cart.php

5

Ok and how can i access the email id of the user in it ?

6

Ok and how can i access the email id of the user in it ?

$cart['user_data']['email']

or

$cart['email']

I do not remember correct variant