Step 2) Go to your business and click on 'Add photos' or anything that will get you in to edit your listing.
Note: If you only have 'Manage' privileges over your Google My Business, click on the 'Manage Location' link towards the bottom of the page over your business page preview.
Step 3) Click on the 'Reviews' tab at the top of the page to show a list of reviews.
Step 4) Find the review you wish to reply to and click on the 'View and reply' link.
You can now directly respond to the review.