The handling of this app is very easy and setting it up takes less than two minutes.
On your PC
Download the program for your PC from my homepage.
Start it with Java.
Open a presentation file. The corresponding application starts automatically (in my case PowerPoint). Don't click anywhere else now. The presentation application needs to be the focused program.
On Your Android Device
Start the app (if you haven't done it, yet).
Connect to a PC (either with WiFi or Bluetooth).
Load a presentation from the PC.
Save the presentation, if you like. So you don't need to load it from the PC again.
Start the presentation.
Use the big preview to move left or right (or use the volume buttons).
Use the small preview to jump to a specific slide.
Click on the big preview to play or pause a video.
Long press the small preview to view a file in full size.