You can download the installation file from http://setiathome.berkeley.edu/. When you run SETI@home on your computer, it will use part of the computer's CPU power, disk space, and network bandwidth. You can control how much of your resources are used by SETI@home, and when it uses them. The work done by your computer contributes to the goals of SETI@home, as described on its web site. The application programs may change from time to time.
You can download some add-on applications here: http://setiathome.berkeley.edu/download_network.php.
Some interesting signals: http://www.setileague.org/photos/homehits.htm.
Remember to join team China.