The latest YODL package can be obtained via anonymous ftp at ftp.icce.rug.nl in the directory /pub/unix/. This location is the primary site; always check there for the newest version. Look for a file called yodl-X.YY.tar.gz, where X.YY is a version number.
Once you have the archive, unpack it in a sources directory (e.g., /usr/src/) with the command:
tar xvzf yodl-X.YY.tar.gz
Then, change directory to the created directory /pub/unix/. Edit the Makefile, if you want to adapt some directory names; the defaults are /usr/local/bin as the place for executables and /usr/local/lib/yodl as the place for macro files. Then type make html-doc to install all and make doc/yodl.html. Alternatively, use make latexdoc to make doc/yodl.tex. Read the documentation at your leisure and have fun with YODL.