let me tell you the whole process of my installation first.
at the beginning I installed kernel 2.4.18(my LAN card is not supported by this kernel), then the base system, then I installed the first CD iso of Debian(3.1). after that I upgraded the kernel to 2.6.7(this supports LAN card), then when I tried setting up the ethernet card with PUMP, an error message said the operation failed.
up to now I was following the instructions on this page step by step:
http://seb.kaleidoskope.de/x31/install.html
I am in my university's computer cluster connecting internet, and I have a static IP address.
the problem is I don't know what exactly my problem is.
thanks for any help.