how can i let that message to be seen by a concerned person only

There is two table in my database for this project.one is tbllogInDetails and another is tblsentMessage. tbllogInDetails consists of user_id, dbusername, dbpassword where user_id is a primary key. And tblsentmessage consists of MsgId,MFrom, MTo, MSub, MMsg, user_id where MsgId is a primary key and user_id is a foriegn key. and the relationship is created between these two table.Now could u plz tell me how to insert values in tblsentmessage . i mean here user_Id is a Forienkey field.how can i insert this in the table.

i have done coding like below, but am gettig an error when i run it.error is "Object reference not set to an instance of an object. " could u plz help me to find what is the problem in it. protected void ShowMessage() { string userid = Session["user_id"].ToString(); string conn = ConfigurationSettings.AppSettings["SqlConn"]; SqlConnection MyConn = new SqlConnection(conn); SqlCommand MyComm = new SqlCommand("select tblSentMessage.MFrom, tblSentMessage.MTo, tblSentMessage.MSub, tblSentMessage.MMsg from tblSentMessage INNER JOIN tblLogInDetails ON tblLogInDetails.user_Id=tblSentMessage.user_Id where tblLogInDetails.user_Id = " + userid + " ", MyConn); MyConn.Open(); SqlDataReader reader = MyComm.ExecuteReader(); reader.Read(); try { GridView1.DataSource = MyComm.ExecuteNonQuery(); GridView1.DataBind(); } catch { } finally { MyComm.Dispose(); MyConn.Close(); reader.Close(); }

thanks for ur reply. but when i did according to ur instrution i got a error which says "the name userid does not exist". i have two table in database name logindetails(userid(primary key),username,password)and sentmesdetails(msgid(primary key), to, from, subject, message, userid(foreign key)) for this project.now i have to show those messages in view page to the concerned person only.how can i write query for it. waiting for ur reply