When creating a subsection you can create as many slides as you need by clicking on the "+" button at the bottom of the left menu. Once you have created several slides, you can move one of them to another position by dragging it to its new location in the menu.
When you click the + button, a side window will appear where you can select one of the slides belonging to the style template for your project. Select the one that best suits your needs and you’ll see that it will appear in your slides menu. Once added to your project you can edit it to your liking.
If you want you also have the possibility of selecting a blank slide, though we recommend that you use the style templates to ensure that your course has a homogeneous appearance.
To know more about the layout and the properties of the slide consult the related article.