The PostgreSQL 7.3 sources can be obtained by
anonymous FTP from ftp://ftp.postgresql.org/pub/postgresql-7.3.tar.gz.
Use a mirror if possible. After you have obtained the file, unpack it:
gunzip postgresql-7.3.tar.gz
tar xf postgresql-7.3.tar
This will create a directory
postgresql-7.3 under the current directory
with the PostgreSQL sources.
Change into that directory for the rest
of the installation procedure.
