Having pre-designed backgrounds with areas for Hotspots on your slides is what we ideally recommend - but you absolutely don't need to! You can set any background you like, or stick with a blank background.
If you'd like to start from scratch on your own - when creating a new showcase, select "New Showcase from template" and there you will be able to use one of our handy templates to begin.
Heres how you set your own backgrounds:
To remove the slide background, click the ‘Remove background’ button. You can then set a different background if desired by following steps 2 & 3 above.
You will need to publish this change in order for it to take effect.