Add section in theme manually

How to add section in theme code manually? Follow the steps below:
​
​Add section code:
​
​1- Go to theme code editor.
​2- Create a new liquid file in 'sections' folder.
​3- Copy the following code:
​
​<div id="trustreviews" class="page-width" data-product-id="{{ product.id }}">
{{ product.metafields.trustreviews.iframe }}
</div>
​
{{ shop.metafields.trustreviews["global_html_body"] }}
​
{% schema %}
{
"name": "TrustReviews Widget",
"presets": [{
"name": "All reviews - Grid",
"category": "Trustreviews"
}]
}
{% endschema %}