They're two completely different products. PhotoDirector is a picture and images app while PowerDirector is a video editor.
To fade the edges of an image to transparent in PowerDirector, all you have to do is place a mask on the photo while it's on the timeline using the Mask Designer. Once you have it sized correctly, set the feather radius to fade away the edges as desired.
See the online help
page for the basics, and you can also click on the video tutorial link when you first open up Mask Designer