How do I add transition effect between slides?

To do this you first need to drag-and-drop photo images from the "Compilation area" (the big screen which may hold many image with blue frame) down to the "Sorter & Viewer area" (the filmstrip located at the bottom of the screen). Then go to the "Effects" mode by clicking the on the "Switch between the Edit & Effects mode" button (located at the top right of your screen). Then click on the "Transition Effects" button to specify the transition you want to add. Remember to click on the checkmark for each photo image.