Awesome handle man (DLLHell...ah, the memories of vb6.0 coding...)
Anyway, first to answer your edit/update/cancel question:
By deafult, each of the buttons (edit/update/cancel) is linked to an event of the datagrid which happen to be (surprise surprise) EditCommand, UpdateCommand, CancelCommand. So if you're having problems getting them to work correctly, check to make sure you're using the right events in the code behind.
Now to the second part, adding an item...
option1:
above/below your datagrid, have a button that says add, and some textboxes or whatever to specify the values. When the user clicks add, the record gets saved to the database, you get your dataset over again, and bind it to the datagrid. This will then include the new item.
I think thats the best way IMHO, mainly because the user can be sure that each item they add is actually saved to the db. You could try and do something where the items just get added to the data grid, and then the users have to hit a button to update any new items, but that gets messy:
- what if they close their browser? new items are gone
- what if they forget they have to update?
- etc.
hth
D'Arcy