The Real Player for Linux you got there is compiled for computers using a x86 CPU (read PCs).
The PS3 has a PowerPC compatible CPU and thus can't use binaries that are compiled for x86.
Try to get packages that are prepared specifically for PowerPC Linux and/or PS3.
In your case download the LiveCD from
here and use
Audacious which is a very nice media-player application.
Later (in your case maybe much later) compile your stuff on the PS3 by getting the sources and building them yourself (make is your friend).
Learn how Linux works and learn how to use Linux to understand what you are doing.
That means a lot of reading and trial and error.
Good places to start:
http://www.linux.org/lessons/beginner/index.html
http://tldp.org/LDP/intro-linux/html/index.html
http://www.linuxquestions.org/
And don't panic, it's just computers not rocket science
