Hello! Im a kind of new person to linux.. but I see that we can make our own Linux using LFS.. now heres my question.. when I run it on my Macbook and get to my root prompt.. i input cfdisk so I can plop this onto a partition.. i first get that the opened disk has read only permissions.. then it gives me a disk (doesnt name it) with 655 ish free MB.. im assuming this is off my Macs hard drive and its just unpartitioned space.. now heres my question.. because I first tried to plug in my USB external drive and install it on there but couldnt.. what do I have to do to install LFS on my computer? Do i need to partition my Macs hard drive or can i put it onto my external drive?

Is your computer able to boot from USB drive? Do you have something like the BIOS on the MacBook? Can you check that? If you can boot from USB, you can install LFS, or any linux system on USB drive.
For that you have to have the usb modules compiled static inside the kernel.

Um.. Macs dont use Bios.. they use whats called EFI.. I dont know if I can boot usb or not.. I know if I boot my mac off my OS X disc I can access my external drive.. would I have to run the USB module on the live LFS disc in order for it to find my drive?

To see your usb drives from linux, you need to install the usb-storage module.
To boot from usb you need the modules to be compiled static obviously since it can't access the usb drive to load the modules before the modules are installed.
You can insert the modules on the live system and access your usb drive.
try modprobe usb-storage

Alright! thanks