SSL implementation caused problem

With regard to the above query, the site is https://shiftworkershealth.com and the old address is https://shiftworkershealth.com.

I just found a helpful article that says:
If the error message states: Warning: Cannot modify header information – headers already sent by (output started at /path/wp-admin/admin-header.php:8) in /path/wp-admin/post.php on line 569, then the problem is at line #8 of admin-header.php, not line #569 of post.php. In this scenario, line #569 of post.php is the victim. It is being affected by the excess whitespace at line #8 of admin-header.php.

So, in this case, I looked up line 2 of index.php and got this:

<?php
/**
 * Front to the WordPress application. This file doesn't do anything, but loads
 * wp-blog-header.php which does and tells WordPress to load the theme.
 *
 * @package WordPress
 */

/**
 * Tells WordPress to load the WordPress theme and output it.
 *
 * @var bool
 */
define('WP_USE_THEMES', true);

/** Loads the WordPress Environment and Template */
require( dirname( __FILE__ ) . '/wp-blog-header.php' );

Can anyone tell me if this is the problem and what I should do about it?