Networking :: Samba conf file modifications

Ok, here's possibly another dumb question from a newbie to DSL.

I'm running it from CD, have installed SAMBA and can access shared directories on my Windows network. But I also want to share directories on the LINUX machine with Windows.

I understand it is necessary to modify the smb.conf file to set up workgroup names etc, but I only seem to be able to open this file in read only mode.

How do I overwrite the default file or how do I save a copy of this file (on USB stick maybe) so that SAMBA picks it up properly?

original here.