Using the Pen tool (P), draw a shape that will become the shading at the bottom of the section. Fill with the same colour as the shading stroke, set the blending mode to Multiply and reduce the opacity to 56%.
Then, in the menu bar, select Effect > Gausian Blur and set it to 30px. Double-click in an empty space on the art board to leave the group.
Repeat steps 11 to 13 for the yellow, green and blue rings of the volcano, changing the colour of the shading to match each layer.
Group all five layers of the volcano by clicking and dragging a box around all of them with the selection tool and then hitting Cmd/Ctrl + G. Then Cmd/Ctrl + C to copy the new group.
Now open up unicorns.psd file on the CD in Photoshop. Select the ‘background elements’ layer in the layers palette and paste Cmd/Ctrl + V the volcano vector object. Select As pixels in the dialog box that pops up.
Position it in line with the splash at the bottom of the large rainbow on the left. Then, in the Layers palette, click and drag the layer onto the Create new layer button at the bottom of the Layers palette to duplicate the layer.