How do I enable the alpha key in the chroma editor so I have transparent background so I can place the video over my webpage ?? when I try I have a black background on the video when my blue screen was?
The Chroma-key effect works with a foreground and background video/image.
In your blue screen video, when you pressed blue box, it had no other image as a background, so everything became black that was once blue by default.
Having an video/image on a lower number track running at the same time as the blue screen video (within the timeline) would allow that video/image to show though.
It wont make that blue screen transparent on an export.
At least, as far as I have ever seen. I am not sure what software does that exactly.