Trouble installing on MacBook

[paras2]

Hi Folks... new to Ubuntu here... been trying to install it onto a 2006 MacBook A1185, but having a ton of trouble doing so. I was able to use another Mac Pro and burn the .iso file onto a DVD. Inserting the DVD, turning on, and holding down Alt doesn't bring up anything... the computer goes straight to the hard drive which is blank and so just gives a big "?". Pressing 'C' doesn't work either. Tried installing onto a USB stick via conversion to .dmg, but still no option to choose another boot target.

Any thoughts / directions?

Thank you.
Paras.