How to update thru proxy?

[belahcene <belahcene@iap-cu.dz>]

Hi every body,
I want to upgrade my system ( or a package) by using the debian network, 
but I need to go thru a proxy, is there a possibility to do it. by 
default the apt-get update tries directly the net.

another question please: I always have "not detected  sound card".  My 
card is and old isa ESS.  Knoppix of course detects it without problem.
after the ( sarge  installation ) , the system gave the error "cannot 
open /dev/dsp ...", the file exists, I gave it the appropriate 
permission rw for all, but the problem stold.
What is the appropriate command to find  soundcard ??
thank you
best regards
bela