Passing Parameters Using Stored Procedure With "where" Clause?

i have created this function with a parameter offset and i want to access the database using stored procedure but the code and stored procedure i have written below is not working...what is the right way to do it??

public bool isoffsetexist(int offset)
{
conn.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "sp_offset1";
SqlDataReader dr = cmd.ExecuteReader();
int i = 0;
while (dr.Read())
{
i++;
}
if (i == 1)
{
conn.Close();
return true;
}
else
{
conn.Close();
return false;
}
}

my stored procedure "sp_offset1" is

CREATE PROCEDURE [dbo].[sp_offset1]
@offset numeric,
@appname varchar(20),
@os varchar(20)
AS
select * from tb_offset
where @offset=" + offset + "