Inquiry:How to install Debian from Internet?

[hadi motamedi]

Dear All
I have my Debian server installed from Debian-31 netinst & businesscard CDs
, but when trying to install Asterisk 1.4 it failed . I thought that my
Debian installation was incomplete. Can you please let me know how to
install a complete Debian 3.1 right from the Internet ? Is there anything
like "yum install" to try with ?
Thank you