This is first question answer..
Declare @D as DateTime
Set @D='4-1-2009'
Declare @E DateTime
SET @E=DATEADD(yy, 1, @D)
This is Second ,check your syntax
ALTER PROCEDURE [dbo].[SP_EMP]
@STARTDATE DATETIME, --4-1-2009 from front end
@ENDDATE DATETIME,
@STARTDATE2 DATETIME
AS
BEGIN
SET @STARTDATE2=DATEADD(yy, 1, @STARTDATE)
SELECT EMPNAME FROM EMP WHERE JOINDATE>@STARTDATE2
----
END