Some people will struggle with Java's layout managers. I have written a layout manager, that I use in my programs, called PercentLayout. The code for this is here and it also needs this.
You just need to take the code from that and include it in your project. Of course, for your assignment, you will keep the copyright notice in, and reference it as you would anything external.
To use PercentLayout:
JPanel panel=new JPanel();
panel.setLayout(new PercentLayout());
panel.add(new JButton(.Top left.),new Constraint(0,0,10,10));
panel.add(new JButton(.Bottom right.),new Constraint(90,90,10,10));
The default behaviour is NOT to stretch the component to fit the area, just to use that area as a maximum size. You can change this:
panel.add(new JTextArea(.Middle.),new Constraint(true,40,40,20,20));