There are two ways to set the background color(s) for your project. You can change it project-wide or by specifying a color per slide.
Setting a Project-Wide Background Color
Click the [Entire project] button and select the desired color.
You'll notice that the selected background color has been applied to the entire project.
*Individual slide colors need to be selected as transparent in order to change the background color of the entire project.
Setting Background Color per Slide
Place the cursor on the slide you want to change and click to select it.
Click the [Current slide] button and select the desired color.
You'll notice that the selected background color has been applied to the selected slide.
How to use chromakey
To use a chromakey background, enable the chromakey option.