1: Download the latest linux kernel sources using git
# mkdir linux-next
# cd linux-next
# git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
linux-2.6

2: Do some modifications.
# pwd
/root/linux-next/linux-2.6

Just a couple of thoughts, Amit - you seem to have your kernel tree in
/root and be doing everything as root, are you sure you want to do it
this way rather than in $HOME as your normal user account?
Also the kernel tree you are using seems to be Linus's mainline, is
that what you wanted or did you want to be making the patch against a
linux-next kernel?

Cheers,
Julie