ASP.NET

SqlConnection conn = new SqlConnection();
conn.ConnectionString = "Your_Connection_String_Here";
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandType = CommandType.Text;
cmd.CommandText = @"INSERT INTO [SupplierOperations ] VALUES (@orderNum, @modelNum, @other);"; // <-- paramaters here named whatever you want.

SqlParameter p1 = new SqlParameter();
p1.SqlDbType = SqlDbType.NVarChar; // <-- didn't bother guessing the db type for this field or the next one
p1.ParameterName = "@orderNum";
p1.Value = txtOrderNum.Text;

SqlParameter p2 = new SqlParameter();
p2.SqlDbType = SqlDbType.NVarChar;
p2.ParameterName = "@modelNum";
p2.Value = txtModelNum.Text;

SqlParameter p3 = new SqlParameter();
p3.SqlDbType = SqlDbType.SmallDateTime; // <-- this is where ado.net automatically converts the value provided to smalldatetime.
p3.ParameterName = "@other";
p3.Value = TextBox1.Text;

cmd.Parameters.AddRange(new SqlParameter[] { p1, p2, p3 });

cmd.ExecuteNonQuery();