very simple, I take it your using firefox.
All you need to do is either download it extract the tar.gz file and then run the flashinstaller in terminal
What a lot of advanced users would do is give you a bunch of commands, first using wget to grab the file and place it into your system then use the extract command and then run the installer, you do this by copying and pasting the following.
wget
http://fpdownload.macromedia.com/get/flashplayer/current/install_flash_player_9_linux.tar.gzthis will place the tar.gz file where you are already located such as /home/john/
tar xvzf install_flash_player_9_linux.tar.gz
This is what you use to then extract the files which will go to install_flash_player_9_linux
cd install_flash_player_9_linux
This command is what is used to then go into that folder
./flashplayer_installer
That is the name of the installer by pasting that in it will then run it and give you a few options, just making you agree to the license and then to select the browser you want to install it to (close your browsers)
