Swing Program - Adding JPanel To JScrollPane

I'm writing a Java Swing program for my software development class to allow a user to create a map for a side scroller video game. I'm stuck on a particular part of my GUI where I'm trying to create a properties box for specific tiles. When I draw the components onto the JPanel and display it as it is, it shows two check boxes per row. On the ScrollPane however, all the check boxes go straight onto one line and draw out the scroll pane. Right now I am only concerned with just making the basic GUI.

Here is what I have so far:

Within the main class, I am creating the JFrame and adding components to it. I am attempting to create a JScrollPane which will hold the properties check boxes...

Here is the method where I am implementing the code. It works, but it doesn't display correctly.

private void createPropertiesBox() {
PropertiesBoxPanel pbp = new PropertiesBoxPanel();
propertiesBox = new JScrollPane(pbp);
propertiesBox.setViewportView(pbp);
frame.add(propertiesBox);

[Code] .....

I've been tinkering with this code for quite some time now and I cannot seem to make a breakthrough on how to fix this.