Introduction
In this tutorial, I will teach you how to add a shining element to a certain object. The technique you will be learning can be used in all sorts of designs and interfaces and even text-effects. You can use it in cell-shaded or realisticly shaded graphics depending on whether or not you use a blur.

To get started
For this tutorial you will be needing a random object to which you would like to apply the shine to. As an example, I used my logo, but as we move along, you'll notice I'll be using a few more objects to show you the various shines we can apply to an object. First you'll be needing that object on a new layer, because we're gonna make usage of the transparency.

The standard shine
Grab your Elliptical Marquee-Tool and draw a pretty flat oval shape on a new layer and fill this with white like below.

Press CTRL+G or CTRL+SHIFT+G to mask the layer with the underlaying layer, in this case being the logo. And as you can see the original shape being changed to outline the shape of the layer it's masking.

You can then proceed to either lower the opacity a little or mix it togetehr with several blending-modes. Below you see the layer with just the blending-mode changed to OVERLAY and below with a lowered opacity.

Check below how you can apply it to various objects and how you can also blur them by going to Filter>Blur>Gaussian Blur and selecting a blur-setting depending on your document-size.

Conclusion
As you can see, you can apply this technique to any object, but do note that if the object has either the blending-modes Color-Overlay or Gradient-Overlay, this cancels out the masking due to the fact that the overlay is placed on top of the mask. You can then lower the opacity of those overlays or play with blending-modes. Play around with it. Thanks for reading and have fun!