The latest Flash Player 10 was released on 15th Oct 2008.If you do not have it installed(check here),you will see how to install it for 64-bit on ubuntu 9.04
First,download the script to your home directory.Open up a terminal and make the script executable by following command:
sudo chmod +x flash10_en.sh
then run it by typing:
sudo sh ./flash10_en.sh
It will close current firefox browser you opened up and download something.
When done,you will see “You may restart Firefox Now” in terminal.