HandBrake is a free DVD to MPEG-4 ripper/converter for Mac OS X 10.3.9 and later. Follow these steps to use HandBrake to convert your DVDs into MP4 format for storage and playback on your hard drive, or for playback on your video-supported iPod, iPhone and Apple TV.
 
1. Download and install HandBrake. Insert the DVD you wish to convert into your Mac's DVD drive. If your Mac's DVD Player application opens, quit the DVD Player application.  
2. Run HandBrake. Select Detected volume. Click Open and wait as HandBrake detects the titles on your DVD. HandBrake will detect all the titles on the DVD. If you're ripping a movie, just select the longest title in the list. If you're ripping a TV show or something with multiple episodes on one disc, then select the episode you want.  

3. Leave the default settings or choose the settings you prefer. For best quality, tick 2-pass encoding. This takes twice as long to encode, but it improves the video quality and doesn't make the file any larger. In Video–Quality, tick Average bitrate and enter 400. This can be as high as 768, but unless you squint you probably won't see much difference. Higher bitrate = higher quality video = larger file size. In Audio-Sample rate (Hz), select 44100. The Sample rate is entirely up to you. Higher sample rate = higher quality audio = larger file size. In Bitrate (kbps), you can keep the default of 128, or select a rate up to 160. Higher rate = higher audio quality = larger file size.  
4. Click Rip. Encoding time depends on the speed of your Mac, the length of the movie, and whether you selected 2-pass encoding. Handbrake will display a progress bar. When the progress bar indicates Done, exit HandBrake. If you are going to watch the converted MP4 file on iPod/iPhone, run iTunes and find the .MP4 file that HandBrake created and drag it into your iTunes library, or select Add to Library… from the File menu and select the encoded movie.  
 
Tips  
 
1. If the converted MP4 file is still very large, for example more than 4.0 GB, you can turn to a compression program for help.  
2. If you center on more powerful functions such as movie length trimming, video cropping, selecting DVD chapters/titles, joining/merging more than one DVD chapter/title, selecting audio track and subtitle, or want to rip DVD's for viewable on more mobile devices on Mac, you can try this Mac DVD ripper for your reference.

I found the step by step user guide about mac dvd ripper here http://www.mac-dvd-ripper.com/guid [...] guide.html