If you want to create a new slide go to the media library and follow the steps below:
- Click the "Add" button at the top left area and click on "New slide".
- Afterwards name your slide and select the resolution for it.
- Now you can set your background color and add some elements by clicking the "+" button at the top left corner.
- At last you can save your slide by clicking the "Save" button and close the Slide designer by clicking the "Close" button.