According to Paul Graham, first I'm supposed to
install version 372 of mzscheme
So I went here: http://download.plt-scheme.org/mzscheme/mz-372-bin-i386-linux-ubuntu-sh.html
sh mz-372-bin-i386-linux-ubuntu.sh
But then when I download that shell script, and follow the instructions, I get the following error:
Checking the integrity of the binary archive... ok.
Unpacking into "/home/n/mz-tmp-install"... done.
mz-372-bin-i386-linux-ubuntu.sh: 478: mz-372-bin-i386-linux-ubuntu.sh:
mz-tmp-install/bin/mzscheme: not found
Error: installation failed
(Removing installation files in /home/n/mz-tmp-install)
I'm not sure how to get that version of mzscheme working on your computer, but I can solve your higher-level problem of "how do I run Arc?"
The latest version of Arc, 3.1, was released in 2009. It no longer requires mzscheme 372 or earlier.
If you download 3.1, you can run Arc on top of Racket with racket -f as.scm. The install instructions on arclanguage.org have not been updated, however.
You might also want to look into anarki, a community-driven fork of Arc, which gets bugfixes and some changes. And the Arc forum has a few people posting in it, if you have other questions.