Installation on Mac

How do I install Ubuntu 9.10 from USB on mac. I got a friend to set up the flashdrive, but when I start my mac and go to the boot screen the flashdrive doesn't appear. Do I need to change a setting?

Installation on Mac

Normally Linux is booted in a Mac from a CD. You have to put the CD in, switch off, restart and press the "C" key to cause it the boot from the CD.

I do not know of any key which would cause it to boot from USB.