When you click on new it will be created a new card with empty or default sql values.
To edit a card you have first to search for it, check the matching row and click on edit.
Select save to save the card values or on copy to make a new card with the same values of the current one. A copy will be identical but with unique ID, a new creation time and a new owner, once you select copy you will be working on the new copied card.
If you select delete, the current card will be permanently deleted from the system, you will be prompted to confirm since afterwards there is no undo or restore ability.
If you are editing a card and the search result are still available the command list will bring you back to the search result list, similarly after delete.