Open iMovie, and you will be prompted to save your new video project. Select Create a New Project. This opens a new window, where you can name your project and select where to save it.
If you're going to save your project on your computer's internal hard drive, be sure there will be enough space for all of the video files. If your hard drive isn't large enough, it's easy to purchase an external hard drive to attach to your computer and store video projects.
