The following is a very long post, and i apologize in advance, but i am new to this operating system, and do not know what i did wrong, so it would help the most, i reasoned, if i told you folks everything
I just installed Ubuntu on my macbook, I successfully went through the ubuntu installer with a friend's help. He had me partition the 10 gigs of space i had left for Ubuntu into two parts. 9 gigs for ubuntu itself, and one gig for the swap (or whatever it's actually called). But, as I realized later, I may not have set a mount point for the mac partition of my hard drive. This may even be the cause of my biggest problem, which follows.
I futzed around in ubuntu, couldn't get wireless ( an issue, but not my biggest), then restarted my macbook to tell him that i had got it working, and even though i held down the alt/option key, i was automatically booted into linux, so i restarted again, this time managed to get into OS X, then restarted again, to try and get wireless in ubuntu ( i held down the alt key, of course, ) but when i got to the menu that used to offer where to start the computer from (and hence, which OS to load), i was unpleasantly surprised. the only choice my computer gave me was the mac portion of my hard drive.
I restarted my macbook several more times, all the while holding my alt key, but with no improvement
I finally gave up my tactic and logged into OS X to look at my hard drive. Disk Utilities told me that there were the three portions i had expected (mac, ubuntu, and swap) but that there was another partition, a third of a gig, and that there was an amount of free space that was, coincident or not, equal to the amount that was taken up by the Ubuntu portion of my hard drive.
I called my friend, he said it had to do with the mac boot code, and that i would probably have to rewrite parts of it, he also said that i should ask the mac-ubuntu forums for help.
I would appreciate any help, thanks in advance.