The beginner needs help

I must be really dumb.  what is the process for adding a reply to an existing 
thread.  Is that a "follow up"?  Do I clear out the text as presented to me 
and just add my comments?  Oh well there must be instructions somewhere!

I had seen a reply (which I can't find now) that discussed setting up a static 
IP and stated the following:

Telnet into your HD1K and cd into the /etc/sysconfig/network-scripts
directory.  Type "ls" and you'll see a file called "ifcfg-eth0.orig".
Hold onto the old ifcfg-eth0 by renaming it to ifcfg-eth0.dhcp or some
such.  Rename the ifcfg-eth0.orig file to ifcfg-eth0 and edit it to
give it the proper IP address, netmask, and gateway for your network.
Save the file, sync, and reboot your HD1K.


It seems I can not write to /etc/sysconfig/network-scripts. Permission is 
denied.  I get that when i try to copy the original ifcfg-eth0.

When I telnet in I am "guest", can I telnet in as root? Do I need a password?

I built a Directory in /home/guest where i put a saved copy of ifcfg-eth0 and 
built the new version, I just can't get it where it needs to be.

I also understand Save the file, and reboot, but what does "sync" mean as 
in "Save the file, sync, and reboot your PC"

I understand all of the principals, just don't know all the key strokes.

help Appreciated