Start a terminal emulator e.g. Konsole or gnome-terminal and then enter the command "amarok" (without quotes). Post any error messages you get. As for mp3 playing capabilities, go to
livna.org and follow the instructions for installing the livna release rpm and gpg key. Afterwards do in a terminal, switch to root using the "su -" command and then do "yum install amarok-extras-nonfree".