The Configure Blog Post window will display a handful of options, and the Reactions feature is near the bottom of the list:
To turn on Reactions just select the checkbox, and then you will be able to customize the feature by adding words of your choosing. Finally, you can choose the exact location of Reactions by dragging the widget at the bottom of the Configure Blog Post page:
You can customize the location of the Reactions within the post by dragging the preview around in the “Arrange Items” box.
You can customize the options and their label to match the theme and style of your blog.