Click the small triangles on the left and bottom panels to minimize them; this will give you the maximum size preview as you make subsequent adjustments. In the panel on the right, much like in Lightroom, begin at the top and work your way down. Use the pulldown menu under Color Filter to add a green filter, which brings out the mist on the pool’s surface. Keep Preserve Luminosity checked to avoid darkening your image.
You can fine tune the density and color of the filter you add, or just tweak it using the Cool/Warm slider.