how we can configure telnet server in linux
 

I have one red hat 5.0 and i want to configure telnet server on it how we can do that

Telnet doesn't have a whole lot in the way of configuration options, it is basically on and off; what exactly are you looking to configure? Or do you mean just starting the server?

Also, is there a particular reason you need to use Telnet rather than SSH? SSH is worlds more secure and capable, there aren't a whole lot of reasons to still be using Telnet in 2009.