In the future - I'd suggest doing a search - as this thread comes up a LOT. (I understand you're new here, just trying to help)
Next - I'd suggest Handbrake. Easy, works great and is for OSX.
I'd suggest the 0.9.2 build as that one will crack DVDs all by itself. The newest version 0.9.3 requires you get VLC and install that into your Applications folder. (not a big deal, as VLC is a great video player anyhow)