Installing modules

[DaugeFa]

Hello,
I'm having troubles with modules !
It will probably sound a bit stupid, but I can't install any module.
For instance, I would like to install NET::POP3
I do :
perl ppm.pl
then, I type install NET-POP3. That asks me if I want to retrieve the packet
NET-POP3, and I answer yes. Then, it tries, but tells me about a HTTP post
failure.
Well, in other words, I can't set up any module. Please HELP me !
What should I type exactly ? should I download something ?
Thanks a lot.

Fabien