Hi Abdul,
 
As I understand you have a working C# etch Console Application, basically a exe which is running properly. To convert that into windows service, what you can do is use normal windows SC (Service Controller) command to create a windows service for that exe. You can google to find ways how to use windows service controller command to create a windows service. However your application should enough logic to take care that the exe will be running all the time when it becomes a windows service and service is in started condition.
 
Other option is to create a visual studio project for windows service in C# and then you follow the steps for creating the etch based application in C#. And move the main file C# code in visual studion C# project main file. I haven't tried this but looks to me that it can be possible.
 
Thanks
Nabhonil.