"Linux From Scratch" is the name of a do-it-yourself distribution where you download every piece of code you want to use and compile it yourself. I doubt if that is what you want.
What do you want to do with Linux? If you want to browse the internet and edit "Word" or "Excel" documents, then just pick one of the top distros from the distrowatch list at http://distrowatch.com/
. Each distro has it own website where you can download their current version, along with instructions for installation. Post back to this forum if you get stuck and need help, since the instructions are not always 100% clear to newbies.
If you are coming from Windows XP, it might be easiest to start with a KDE based distro like Kubuntu, PCLinuxOS, or Mandriva. Some folks swear by Gnome or Xfce and you might see some "which is best" battles on the forum. The fact is that the best system is the one that work best for you. They're all good. You'll get the most help if you stick to the distros near the top of the list since that is what the most people are using.
If your expected use of your computer is to play the games that you get in shrink-wrapped packages, you are probably better off sticking with Windows.