Is the problem that you can open the footage rendered from VisionLab in iMovie, or that you are having trouble figuring out how to export the footage?
Assuming you are just looking for how to export the footage, the process of permanently embedding the effects you have created into the video file is called Rendering
, and can be accessed via the Render menu. Use this command to export a new video file with all of your effects included. You can then open that file in iMovie or whatever other video software you want.