Assumes your wireless card is properly detected by Ubuntu 9.10.
- Click on the network icon on your taskbar on the top
- Click on your wireless network => Ubuntu should then prompt you for the network key
- Simply enter your network key then press Connect
- You are done!
NOTE: If you are experiencing ubuntu 9.10 wireless problems, please try this solution shared by Jon: http://ubuntuforums.org/showthread.php?t=1288865