How to add page handle to body class?

You will need to add this code to your meta-tags.liquid and follow the instruction below.
{% if handle == 'your-page-handle' %} {%- capture og_image_tags -%}<meta property="og:image" content="link-to-your-image">{%- endcapture -%} {%- capture og_image_secure_url_tags -%}<meta property="og:image:secure_url" content="link-to-your-image">{%- endcapture -%} {% endif %}

after that you just need to follow this guide below