Shortcode function – replacing echo with return – need help

Hello, I’m new to writing WP plugins and after I wrote this code, I saw that the code is executed before the content of the page. Now I know I should had used return instead of echo. Any help how can I change the code? I am a real php beginner ??

<?php
$permalink = get_permalink();
$now = time();
$compare_time = mktime(0, 0, 0, 1, 1, 2016);
$post_time = get_post_time('U');
$url03 = str_replace('https://', 'https://', $permalink );

if ($post_time < $compare_time) {

echo '<div class="g-comments" data-href="';
echo $url03 . '"';
echo ' data-width="700" ';
echo 'data-first_party_property="BLOGGER" ';
echo 'data-view_type="FILTERED_POSTMOD">';
echo '</div> ';

}
else {

echo '<div class="g-comments" data-href="';
echo the_permalink() . '"';
echo ' data-width="700" ';
echo 'data-first_party_property="BLOGGER" ';
echo 'data-view_type="FILTERED_POSTMOD">';
echo '</div> ';
}
?>