Possible Duplicate:
Objective C for Windows
iPhone development on Windows
How do i setup and write Objective-C on my Windows Vista (32 bit) machine?
Can someone please give me instructions?
You can use GNUStep http://www.gnustep.org/. You can also use Eclipse CDT with GNUStep, see configuration here http://wirecode.blogspot.com/2007/11/objective-c-and-eclipse.html