Hello friend..
You got that error because you have create a web serive and also code for calling that service in you windows application....
but before you call your service method you need to run your service on either on II7 or on your VS IIS,
after your web service is online using this then you can not face this problem....
or for more detail on how to call web service in windows form please see this...
Webservice with Win Forms and Web Forms[
^]
Consuming Webservice In A Windows Application[
^]