Button value and Assignment to Text Box: Student Query

I am trying to assign JButtons double (currency) values, perform simple add methods from other similar JButtons, then send the result to a JTextBox. With some JButtons the value will go directly to the JTextBox display.

This is my second assignment and is due today. I have really tried to solve this on my own. I did accomplish creating a tabbed pane GUI displaying all of the JButtons with Icons, etc. The final display would ideally resemble a cash-register with tape output.

Thanks sincerely for any timely assistance. I will help others once I am able to. pdqh