Events are like folders in the iMovie library that hold the clips that you have imported into iMovie. Everything that you import into iMovie is contained in the iMovie Library. You can view all the clips as a batch in the Media Browser by clicking on iMovie Library in the Media sidebar, and you can also view them partitioned into separate events.
Events can only be in libraries.
When you click on File/New Movie, a new movie project will open where you can add your clips from events into it and edit them to create a movie, and then share out the project as a stand-a-lone movie file, or to the Theater, or to selected online video websites. You can also create a project from the Projects browser screen view by clicking on the grey square with the + sign in it titled "create new". A project is the same as a "new movie" that is unfinalized and in the process of being edited. Here are some links that will help you understand how iMovie works:
iMovie online help menu:
Organize Media and Events:
Create a New Movie:
Consolidate projects and events: