You can draw any polygon with:
g.drawPolygon(int xPoints, int yPoints, int numPoints)
If you just type "g.draw" on eclipse it will show you plenty of options.
You can create more complex shapes by using a combination of multiple shapes.
g.fillArc(x, y, dotSize, dotSize, 5, 150);
Don't also forget that the instruction says you can create wavy pictures.