You can make the background of your text box different colors.
To do this, click on the text element you're working with.
In the right-side Properties panel, there's a section towards the bottom called "Textbox."
If you click on that, it will open the the option to use either "Fill" or "Stroke."
Fill will turn the entire text box into the color you select, like you see in the screenshot above.
Stroke creates a border on the text box the color you select, with a pixel width you specify.