about trigger

Welcome to the forum!
First of all you cannot call a trigger directly from C# (or even T-SQL, for that matter). A trigger is fired when a certain event is raised, such as an INSERT. A very basic skeleton for an INSERT trigger probably would look like this:
CREATE TRIGGER dbo.SomeFancyTrigger ON dbo.SomeFancyTable
AFTER INSERT, UPDATE
AS
INSERT INTO dbo.SomeFancyOtherTable
(...)
SELECT
...
FROM
INSERTED;
GO
You can find more on triggers here: CREATE TRIGGER

Welcome to the forums.
As referred by Frank the triggers are database objects which will fire from server end, see http://msdn.microsoft.com/en-us/library/ms189799.aspx also for more information.