how to use COUNT in c# windows application

Question

Hii

I am new to C#.net

I have a application in which i have search option(Button)

I first want to check in database if any data is available which user has entered for search.
  if it is i want to show that data

otherwise i want to display an error message.

i know this can be done by count function but i am confused how to use it and how to use it to check in if condition

Please help me in this problem

Thanks in advance
Rahul patel