First you'll need to register or log-in.  Then navigate to the restaurant you want to review.  For example, if you want to review Red Robin Gourmet Burgers, you go to restaurants, and then click on R to help narrow down your selection.  Once you've looked through the R's and found the restaurant, click on the name to open up their page.  Look toward the bottom of the page and you will see a button that says write review. Click on it, write your review, rate the eatery, and then click send.  It's just that easy!  You can also look for restaurants by cuisine, click on type (example: burgers), and follow the same steps accordingly.