Once you finish making a video in iMovie, there's not a lot you have to do to put it into iDVD, but there are a few things you might want to do. The most fun of all the options is to add chapters to your movie. (Chapters are midpoints in your video that can be directly accessed from the opening DVD menu.) This way, for longer videos, you can choose between playing from the start or popping to specific locations within the movie, which saves you from having to fast-forward every time you want to watch a certain part of the video.
None of Jennifer's videos is long enough to really merit chapters, but since adding them is easy enough, it's worth seeing how it's done.