Newby, need help installing codecs (mp3, mpg, avi-divx,xvid, dvd, etc) and skype

Newby, I need step by step help with installing codecs (mp3, mpg, mpeg, avi-divx,xvid, dvd, mod, vob, etc)

Cannot play mp3, videos and dvd. Please help getting/installing codecs above.

Also need help installing/setting up Skype.

Thanks.

Not skype
But
Multi-media and Restricted Format Installation Guide