how can i call web service with its URL in c#

I have a web service and windows form project that have two textboxs and a button.My web service has two parameters and it checks this values exist in database or not.So I write values to textbooks and press button.I want to call my web service and it gives answer me when I pressed button. But I want to call web service with its URL. Please help me immediately..

PS: Excume me for my bad English(