IMovie
From charlesreid1
Importing Video
When you import video, it creates an event in the event library.
Creating A Video
You create a video via a project. The project portion of the window contains the various video clips, transitions, and sound bytes that compose the project.
Add Music, Photographs, or Titles
On the right side of the iMovie window, below the video viewer, are a set of icons. Three of them will allow you to insert music, photographs, or text/titles. You can click on each one, and it will bring up a music/photograph browser, or a list of styles for text and titles.
Transitions
You can cut, slice, and combine various video clips from different events (or even a video clip from a single event). Transitions provide a "pretty" way of switching between these video clips.
In the set of icons below the video viewer is an icon for transitions. This allows you to browse among different transitions and insert them into the project. These include transitions like a fade to black, fade in/out, slide left/right, etc.
By dragging and dropping, you can insert the transitions wherever in your project you'd like. You can hover over the transition, and click the cog wheel that shows up, in order to modify the settings related to that transition (amount of time, etc.)