JFileChooser only give you a list  of files  you had
not. You still have to use file  read and write.
There are more complicate way to search and retrieve
files, but stick with the basic just to see if it's
working out OK.

ok thanks. What is my best option... FileReader or FileOutputStream or something
like that? How many lines of code  do you reckon it should take?

for text file  you should use FileReader and for binary , you could use
FileInputStream...

code is like :
try {
reader = new BufferedReader(new FileReader(fileName));
} catch (FileNotFoundException e) {e.printStackTrace();}

then you could read it line by line using method BufferedReader.readLine() ;