Here is a good comprehensive article on the subject
OK, bear in mind that your question very unclear - and it doesn't seem like you've gone through the effort of actually looking on this site for possible answers to your query.
Here is a link to a more useful place for learning with your slightly expanded explanation about your problem:
how to pass query by date SQL Server in C# coding
Beginners guide to accessing SQL Server through C#
Enjoy, and remember good questions gives good answers.