trainticket

I am trying to do email functionality (For my learning purpose)using spring. Here is the code snippets:

I've used JDatePicker for a simple app, but my teacher said that he will accept no precompiled .jar's, and he needs to see how it's able to compile from just sources.
So I checkout JDatePicker source code, extract it, and add every .java file from the extracted directory to my BueJ project. I had to remove some imports inside those extracted classes, so that JVM will "look inside project".
Now BlueJ can not find where classes JDatePickerImpl & JDatePanelImpl are defined...
And neither can I. If I grep -rn through project folder all I get is two lines of my own code.
Can anybody suggest how to import classes that are supposed to be there, just can't find definitions? Maybe, I should write an "implementation" (hence the Impl in name)?

Here's uploaded project
The only file written by me is TrainTicket.java

We're trying to create a money management app. Therefor we have made a TableView in which the user can add their spendings. They can choose in which categorie their spending belongs, such as clothing, traintickets ect. We now have created a piechart in which we would like to display on which categorie the user has spend most of his money on. To get the data for this chart we need the amount of cells with those certain images in the table view.

So we want the app to count the amount of cells with for example the image clothing.png in it.