<p>I am having a .cs file, i need to execute that file.. 
I don't have experience in C#.. Please help.. Do we have to install any software to run it.. </p>

<p>Currently i am using windows XP.. </p>

<p>Please help me... </p>

Grab the
.NET SDK
(perhaps not needed, see comments) and see if you can compile your .cs file with
CSC.exe
Alternatively try Visual
Studio Express Edition
But if you don't have ANY experience with software engineering, this might not be the best way to start...