how do I collage two or more videos into one shot?

To put two videos on the screen you have a couple of options.

First, go to iMovie/Preferences and make sure that the Advanced Tools are enabled.

Now, you can add the first video clip to the project. Drag the second video clip and drop it in the project on the frame of video where you want it to start. A popup menu will appear. Here you can choose several options, including Cutaway, Picture In Picture, Side By Side, etc.

For what you are describing, I might try using a Cutaway. Then go into the Inspector for the Cutaway Clip by clicking on the gear wheel icon in the clip. Then adjust the Opacity Slider so you can see both clips at once.

I find the new iMovie very easy to use, but it is quite different from the old iMovie. It is worth spending some time to learn the new interface. David Pogue/s Missing Manual book is good, but before you spend money on it, I recommend that you spend some time with the following resources.

iMovie 08 Video Tutorials

iMovie 09 Video Tutorials

iMovie 11 Video Tutorials are embedded in the iMovie/Help.

iMovie 09 Tutorial from Ken Stone

iMovie 11 New Features.

Hi, besides using iMovie, there are other easy tools for non-technical folks to make video collage. You can add any kinds of footage such as images, music, videos. Also, you may create the video more vividly by adding transitions, overlays, texts and so on. All you need to do is to drag and drop the material to corresponding timelines.

Hi,

In iMovie 10.x.x you use the Cutaway feature for that.

This help link will show you how to do it.

http://help.apple.com/imovie/mac/10.1/#/movf525350f0

-- Rich