Here is some information on how to set up a chroma keying (e.g. blue screen/green screen) project in Movie Edit Pro:

First of all, you need to make sure that you have source material that is suitable for a chroma keying effect. Movie Edit Pro supports a few different background colours for the chroma keying effect, including the two most commonly used ones - blue and green. Once you got suitable footage shot in front of e.g. a blue or green screen, it's actually a relatively short and easy way in Movie Edit Pro until you can see the first results. Just import the video (or still picture) that is supposed to constitute the background in your resulting project into Movie Edit Pro. Make sure you're operating in timeline mode. Now, import your footage shot in front of the coloured background that is supposed to constitute the overlay into the program and place it parallel to the background video/picture on a track with a higher track number. There is a priority system behind the tracks in Movie Edit Pro, where a higher track number equals a higher priority. At first, the imported blue/green screen object will still completely conceal the background object. So, the next step would be to go into the "Video effects" dialogue for the foreground/overlay object (e.g. by right-clicking on it and choosing the video effects from the context menu that will come up). Here you can activate the chroma keying in the lower Mix FX section and choose what colour is supposed to be used for the keying (e.g. blue box, green box). In addition to can manipulate the threshold and fading range slider to finetune the effect, which might especially be necessary if you shot the footage in front front of a screen or under lighting conditions that were far from ideal. Once you're done, just confirm the dialogue and you're reading to preview your result in the Movie Edit Pro arranger.

I hope this helps to get you started.