To replace a green screen background in CyberLink PowerDirector, follow the steps below:

1. Place the media clip that want to be display as background on Track 1.
2. Place the media clip with the green screen background on Track 2.
   
3. Double click on the clip with the green screen background to open in the PiP Designer.
4. Select the Chroma Key tab and then Enable chroma key
5. Click on the eye dropper button on the Chroma Key tab and then select the (green) color in the image or video clip that you want to replace/make transparent.
   
6. Adjust the Tolerance of hue, Tolerance of saturation, and Tolerance of luminance sliders to remove the selected color/background (green  screen). Adjust until the image or video behind your PiP media is completely revealed, without any loss of quality on the PiP media.
   

Note: The user interface in the snapshots might differ slightly among PowerDirector versions.