BleepingComputer.com: transaction file

hello,
i am currently working on a IT Project and i have created a database using a java software called "JBuilder". the topic i have chosen my project is about a phoneshop n i am going to develope a databse software which will allow them to search for phone, display stock, edit price, delete a phone, add a phone etc.

i have already made a complete system which does all the above function with a graphical interface. however i am trying to add another application in the same database for trasaction. for example if the employee sells a phone i want the phone to add on the transaction file and also the date. on my trsaction file im going to record the phone name & the model number, the serial number of the phone and a ref number and also the date.

could you please show me the right structure and how i should start the program or just give me a example based on my project im doing.

Thank you.