Click on the Mail Merge button on the upper left corner of your Gmail.
You will open the Mail Merge List page. Clicking the Create New Mail Merge button will bring you to the Set Recipients Page.
Another area from where you can send a mail merge campaign is in your sidebar. Go to the homepage view of the sidebar to get a list of all your Google Contacts groups. You can send bulk emails to any of them. Click on the triple horizontal dots beside the name of the group. From the menu that appears, choose the option Mail Merge. This will open the Set Recipients page.