Right-click

Right-click on the slide panel, you will see pop-up menu as follows:

Add Photos: select photos in the file browse pane and add them to your slideshow.

Remove Selected Photos: right-click on your selected slide and choose this option in the menu and then the selected slide will be removed from the slideshow.

Transition: you can choose transition effect for your selected slide from the pop-up list.

View Image Options: choose this option to view the Image Options window and configure the settings of the selected slide.