How do I use green screen effects in cyberlink powerdirector and put the video in the green part?
Summarizing from How do I use the chroma key feature to replace a green screen background in CyberLink PowerDirector?:


Put the video or image you want to use as the background (what will replace the green) on Track 1.
Put the video that has the green screen on Track 2.
Double click on the clip with the green screen background to open in the PiP Designer.
Select the Chroma Key tab and then Enable chroma key
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.
Adjust the sliders until the green completely disappears.


This video might help explain it better.