There are a number of different ways to add individual slides to your presentation

1) Click the SLIDE menu → Click NEW SLIDE

2) Click the + in the TOP LEFT and then you can choose the style of your slide (Title & Body, Blank etc). This is always my choice as you can then control the type of slide you are adding.

3) You can click CONTROL + M and it will add a new slide the same style as the slide above

There are a couple of ways to delete slides.

The easiest way is to click on the small preview of the slide on the left hand side and then click DELETE (or BACKSPACE).

The other way is to click the SLIDE menu and then click DELETE SLIDE.

Duplicate means make a copy that is exactly the same.

If you are adding slides that are the same (or similar) you can duplicate them instead of making them all over again.

This is really helpful if you are using slides to create an animation (you can duplicate the slide and move your character a little each time)

To do this, click the SLIDE menu and then click DUPLICATE SLIDE.