You can add text boxes where it says Text in the sidebar on the left. 

When you can click on "Edit Text Styling" and you'll see a variety of editing options. 

In this step, you can add or remove a background color for your font and change the transparency of the font background.

You can also choose a color to add a text shadow as well as adjust the transparency of the text shadow.

You can round the corners of the text box and add a border to your text box.