1.how i can delete a record at my grid viamy gird .

All you need to do is to make the delete mark visible. Then, in the DELETED() event, if you have DELETED SET ON, you can move the record pointer if you want the deleted record to disappear from the grid.

2.if i have at mygrid two fields as quantity and price,if change any one of them i need new result at another field as total.

In the Valid() method of each of the 2 text boxes in the grid, call a form method that has this code in it:

REPLACE total WITH quantity * price IN << My Grid's RecordSource >>