Step 1: On Admin Panel, Click on Configure>>Catalog>> products >>Allow Guest Review
Once this is done the review will be visible at the front end as shown below:
When Customer clicks on Write Review, the next page that will open will look like this: where they enter the title, name and comment of the review
Step 2: On the Admin Panel, Click on Customer>>Reviews>>Select Review to approve or disapprove the review.
If the review has been approved you will find the review at the down part of the front end product page as shown below:-