What do you want to do in general?
if you want to select some specific rows from the datagridview to insert their values in the database you can loop using foreach through just the datagridview selected rows and not all the datagridview rows like:
foreach(DataGridViewRow dgvRow in yourDataGridView.SelectedRows)
// TODO: code to insert data in the database
Your insert statement specified only three columns within the 'fare_table' while you are inserting many values. The values to be inserted must match the number of columns you specified within the table and if you want to insert more than one value within the same column you should put them together like
INSERT INTO dbo.fare_table(fromsector,sectorto,farebasis) VALUES(value1, value2, value3+value4)
Notice value3 and value 4 have no comma to separate them so there values will be add together in the column farebasis.