Heres a quick run through. First head over to http://easyurpmi.zarb.org/
Go through that. Choose the version of mandriva you are using. Tick all the boxes and choose a mirror closest to you or what ever mirror you prefer from the lists. Wehn you have set up the mirrors you want hit the procede to step 3 button. Open a terminal type su, it will ask you to input your root pass word. Then at the bottom of thatsite paste in the text you generated by pressing step 3. wait a while while it adds all the sources. Wehn its finnished close the terminel. Go to k menu>system>configuration>packaging then clikc install software. Then from there you can search and install software. Type in the search box libdvdscc and it will it wil lfind it, tick the box next to it then hit install and it will download and install it all for you. Same goes for any other piece of software thats available in the database.
There other threads posted around this section that explain it alot better then i do (not particularally good at explaining)