Step. 1 Add file for review.

Please add below code to theme before  </body>tag over. 
{% include 'th-product-review' %}

Step. 2 Add reviews to your product pages

To display product review section, Please add below code at your product template or product sectionat any desired location
<div id="wc_review_section" class="wc_review_main_content" data-url="{{ shop.url }}" data-handle="{{ product.handle }}" data-limit="0"></div> 

Step. 3 Display average star rating badge to your collection pages or product page.

Copy the following code snippet to your clipboard: 
<div class="wc_product_review_badge" data-handle="{{ product.handle }}"></div>

Find your product grid snippet file from below list: