kudinovfedor / fk-google-tag-manager

Google Tag Manager (GTM) plugin for Wordpress

Upload fk-google-tag-manager to the /wp-content/plugins/ directory

Activate the plugin through the 'Plugins' menu in WordPress

Add a hook do_action('wp_body') after opening tag <body>

<body>
<?php echo do_action('wp_body'); ?>
... other code

Go to Settings > General and set the ID from your Google Tag Manager account.

Use comma without space (,) to enter multiple IDs.