First, you probably want to use the stable 5.8.4 (http://www.cpan.org/src/stable.tar.gz) instead of 5.8.3. If you really want 5.8.3, then go find it at http://www.cpan.org/src/5.0/perl-5.8.3.tar.gz:

1. Download the source.
2. You should get the checksum file too, and compare it.
3. unpack it with gunzip stable.tar.gz; tar xf stable.tar
4. cd perl-5.8.4
5. Go look at the README file, and the README.xxx file for your OS.
6. Do what the INSTALL file says to do.

However, before you take step 6, decide whether you are installing over the existing Perl, or installing a parallel version, and where it might go etc.