>>153まずここが分からないです！
unpack the tarball:
bzip2 -cd sbcl-1.0.56-x86-linux-binary.tar.bz2 | tar xvf -
replacing sbcl-1.0.56-x86-linux-binary.tar.bz2 with the name of the tarball you downloaded. Then enter the directory which was unpacked, and run the installation script to install SBCL in your /usr/local directory:
cd sbcl-1.0.56-x86-linux
sh install.sh