Best way to implement software by task using only Java standard API

I have task to implement software using java standart API:

The task is about Decathlon competition. The input of the Java program is a CSV-like text file (see the attachment). The task is to output an XML file with all athletes in ascending order of their places, containing all the input data plus total score and the place in the competition (in case of equal scores, athletes must share the places, e.g. 3-4 and 3-4 instead of 3 and 4). Input and output file names should be provided as parameters to the Java application at the startup. It would be great if an XSL file for viewing the produced XML nicely using a web browser is also provided. Be sure to keep the code design simple, but allowing to easily change or add more input sources and/or output file formats. Unit tests for the code are mandatory. No external libraries are allowed in addition to the Java standard API except JUnit. Keep in mind that we are going to run both your program and the tests. Try to keep your code as readable as possible. We value code simplicity. Use object-oriented approach with design patterns where applicable.

Firstly, what classes recommend to use for upload csv file, and output xml?

Maybe recommend about classes structure? interfaces? and what designs patterns I can use to do this task elegant?

And not very clear for me what I should to do to complete this part of task:

It would be great if an XSL file for viewing the produced XML nicely using a web browser is also provided.