Download one of the free software programs for converting DVDs into digital files for iTunes. The best known is HandBrake. MediaFork is another. The two programs are now one and the same, but depending on your computer's operating system, you may need an earlier version of Handbrake or MediaFork.
Insert a DVD into your computer's drive and open HandBrake. If your computer's settings automatically open the DVD player when a disc is inserted, quit the DVD player. When HandBrake is open, it will detect and display the DVD's contents. You will then decide whether to copy part of the DVD or the entire contents. For example, you may choose to copy the movie itself rather than the special features.
Click "Start" ("Rip" in MediaFork) to begin the copying process. HandBrake will then begin converting the content from your DVD into a video format compatible with iTunes. The time needed to make the MPEG-4 file varies with the length of the movie, but generally takes 30 minutes to one hour.
Open iTunes and drag the completed video file from your desktop to the "Movies" or "TV Shows" section of your iTunes library. The size of the video file varies with the length of the content being copied. In general, however, most movies will be around 1 GB in size.
Connect your iPod or iPhone to your computer and sync your new video file. View and enjoy.