Apparently you are new to UNIX, you have to learn some
rudimentary unix commands. I found a good web site that
teaches UNIX which is geared toward web publishing using
UNIX as a platform.

http://wdvl.com/Internet/UNIX/Intro/toc.html

: (I am not good at Unix programming)I have joined as a
: webdeveloper in a reputed company.
: I was given the login name and password to update some
: files in their website and I was logged on a remote
: system.
: Can u please help me by saying what r the
: commands to overwrite a file or can u give a brief
: description as how to update the existing file?