Here's one way to make the grass greener (although in Photoshop there are always lots of different ways to get the same effect):
1. Add a
Color Balance adjustment layer above your original image (
Layer >
New Adjustment Layer >
Color Balance...)
2. In the Color Balance dialog box, do the following:
- Uncheck Preserve Luminosity
- Ensure that Midtones is checked
- In the Color Levels boxes, type: 0 (left box) +20 (middle box) and -100 (right box)
- Click OK
This will give your whole image a green cast, but don't worry.
3. Click on the adjustment layer's Layer Mask thumbnail in the Layers palette.
4. Select
Edit >
Fill... and fill the layer mask with
Black. The green colour will disappear, but again, don't worry.
5. Now make
White your foreground colour, select a soft-edged brush for the
Brush tool and paint on the layer mask where you want the green colour to show through. You can paint in different shades of grey to subdue the colour effect in some areas if you like. You can also try playing around with
Black to White gradients.
Obviously, since this is an adjustment layer, you can alter the colour at any time just by double-clicking the Color Balance layer thumbnail to bring up the dialog box. You could also try other adjustment layers such as
Hue/Saturation or
Selective Color instead of Color Balance.
As for covering up the area at the bottom of the photo: why not just crop it out? If you select the
Crop tool, click outside the photo at the top left and drag down and to the right, you can position the bottom of the crop area along the underside of the stone bench (careful not to cut the kids' fingers off!). I'm a big fan of Occam's Razor - the simplest solution is usually the best.
Hope this helps - any questions, feel free to ask.