Build.PL problem

[John Rose <..hidden..>]

I'm using Ubuntu Hardy. I've followed some rather out of date instructions for Ubuntu Dapper. Everything OK (including Postgresql). As I already have Apache2 running, I took the 'code' from the ledgersmb httpd conf file and created a new virtual (apache) conf file. Apache2 was happy on reload. 

However, on trying to run Build.PL with sudo perl Build.PL (similarly for login.pl), I get:
Can't locate Module/Build.pm in @INC (@INC contains: /etc/perl /usr/local/lib/perl/5.8.8 /usr/local/share/perl/5.8.8 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.8 /usr/share/perl/5.8 /usr/local/lib/site_perl .) at Build.PL line 4.
BEGIN failed--compilation aborted at Build.PL line 4.

Can anyone tell me what I need to do in order to run Build.PL?
PS I have no knowledge of PERL.

Regards,
John