First, let's start with telling you that it is possible to build LFS on only one partition, which is where your original distribution is installed. This is not recommended if it is the first time you try LFS, but may be useful if you are short on disk space. If you feel brave, take a look at the Install LFS next to existing systems on the same partition hint at http://hints.linuxfromscratch.org/hints/lfs_next_to_existing_systems.txt
Before we can build our new Linux system, we need to have an empty Linux partition on which we can build our new system. We recommend a partition size of around 1 GB. This gives enough space to store all the tarballs and to compile all packages without worrying about running out of the necessary temporary disk space. But you probably want more space than that if you plan to use the LFS system as your primary Linux system. If that's the case you'd want more space so you can install additional software. If a Linux Native partition is already available, this subsection can be skipped.
The cfdisk program (or another fdisk like program you prefer) is to be started with the appropriate hard disk as the option (like /dev/hda if a new partition is to be created on the primary master IDE disk). It is used to create a Linux Native partition, write the partition table and exit the cfdisk program. Please refer to the documentation that comes with your fdisk program of choice (the man pages are often a good place to start) and read the procedures about how to create a new Linux native partition and how to write the partition table.
The new partition's designation should be remembered. It could be something like hda11. This newly created partition will be referred to as the LFS partition in this book.