Here's a little tutorial on how to make simple Shades for a tux in Photoshop 
For making shades as shown in this figure:

follow these steps:
1. Create a new 256/256px white background document in Photoshop and put a G2 tux in the middle (X:128px Y:128px) , click here to get a transparent PNG of G2 tux .
2. Use Pen Tool to create a shape like one shown in this picture:

If you are new to the pen tool then you must give a look at thisor this tutorial.
3. Once the shape is created you need to clip it to smooth , the shape layer would be named as Shape 1 , 'Ctrl+Click' on this layer to load its selection and fill this selection on a new channel with white color.
4. With the new channel selected (Alpha 1) go to 'Filter->Blur->Gaussian Blur' and apply a blur of 1 px , press 'Ctrl+F' to repeat this filter on the same channel.
5. Press 'Ctrl+L' and apply these values for the levels:

6. 'Ctrl+Click' on the Alpha 1 channel and fill the selecton twice on a new layer say Shades .
7. Set the 'Fill Opacity' of Shades layer to '0' , go to its 'Blending Options' and apply these settings in their respective options:


8. Copy this layer (Ctrl+J) and merge the copied layer with a new layer , Select the merged layer and go to 'Layer->Transform->Flip Hoizontal' and move it over the right eye .
That's it
, you can download the PSD file from here
I hope you find it simple enough to follow easily without any obstacles
, waiting for your results 
EDIT
The other part of the tutorial will be posted soon 