Two things...
First...
Your if
statement is ending in ;
if (row == 0);
This is effectively ignoring the statement altogether.
Second, you never seem to add the panel
to the UI...
//...
JLabel panel = new JLabel(new ImageIcon("/Users/Downloads/pieces/EmptySquare.jpg") );
} // End of for-loop...
Consider using ImageIO.read
instead of ImageIcon
as it will provide more details if the image can't be loaded. Take a look at Reading/Loading an Image for more details...