"yum install flash-plugin.i386" without quotes from a terminal window. then you'll need to find the directory where you have your browser installed. If you use Firefox then "normally" but not always, it'll be /usr/lib/firefox.
So what you'll need to do is create a symlink (a shortcut if you speak windows) of the plugin into the firefox plugin directory. You can do this by issuing this command at a terminal window once you have the the flash plugin installed "ln -s /usr/lib/flash-plugin/libflashplayer.so /usr/lib/firefox/plugins" without quotes. If you get an error file/directory not found that is probably b/c that is not the correct path to your firefox installation. Please double click on your home icon on your desktop, navigate to the root directory, double click on "usr" folder, then "lib" folder, and look for firefox in there. It shouldn't be hard. Then replace the path I wrote above for firefox with the one that is correct for your system. All of this should be done as ROOT user. You can simply type "su - root" from a terminal window, enter the root password and ur now root. PLEASE DO NOT LOG INTO YOUR LINUX INSTALLATION AS ROOT. That should never be done, it's a no no.