We are going to build the LFS system by using an already installed Linux distribution such as Debian, SuSe, Slackware, Mandrake, RedHat, etc. There is no need to have any kind of bootdisk. We will use an existing Linux system as the base (since we need a compiler, linker, text editor, and other tools).
After you have downloaded the necessary packages that make up an LFS system you will create a new Linux native partition onto which the LFS system will be installed.
The next step, chapter 5, will be the installation of a number of packages that are statically linked and installed on the LFS partition. These packages form a basic development suite which will be used to install the actual system, and are also needed to resolve circular dependencies. Examples of circular dependencies are: you need a compiler to install a compiler. You need a shell in order to install a shell. And so on.
Chapter 6 installs the actual base system. We use the chroot program to start a new shell whose root directory will be set to the LFS partition. This, in essence, is the same as rebooting and having the kernel mount the LFS partition as the root partition. The reason that we don't actually reboot, but instead chroot, is that this way you can still use your host system. While software is being installed you can simply switch to a different VC (Virtual Console) or X desktop and continue using your computer as you normally would.
When all the software is installed, chapter 7 will setup the boot scripts. Chapter 8 will setup the Linux boot loader and in chapter 9 there are some pointers what you can do after you finish the book. Then you can finally reboot your system into your new LFS system, and start to really use it.
This is the process in a nutshell. Detailed information on the steps you are taking are provided in the chapters as you go through them. If something isn't completely clear yet, don't worry. It will become very clear shortly.
Please read chapter 2 carefully as it explains a few important things you need to be aware of before you work your way through chapters 5 and above.