Newbie question: DHCP set up

[sleepless <hagerbenmahmoud@gmail.com>]

Hello,

I've just started using Debian on my machine (which dual boots with
Windoze - need to keep it for work)... I've been using Knoppix for a
while but wanted to have a more permanent system. My friend helped me
with the setup but since we did it in his home, the DHCP points to his
IP/Router... How do I release it and reconfigure my laptop to capture
an IP? I use cable modem...

I am sure this is a very basic question,so please be patient with a newbie :)

Cheers,
Hager