How use Event handler to collect data from a jframe into the datab

i started a project at school but not sure of what am doing
am designing a shop records system, that takes item name and price from the shop attendant
and when enter is hit this 2 data goes into the database.
the project also include, a calculation of balance button. with few menu and menu items
apparently, i have developed the interface but finding it difficult to come out with the event handlers
PLEAS HELP ME