In this tutorial I'll show how to put water in your can. This is the original picture from where I started this tutorial:
Open the picture of your can (or anything you want to put water in the surface), create a new layer, call it "water", and with the Elipse Marquee Tool (M), make elipses like the picture. Fill them with any color (alt+f)
Now in the "water" layer, right click of the mouse on it and go to Blending Options.
Apply this settings:
Now that you have the style, still on the Blending Options tab, go to the main part and click on "New Style", give a name to it, this way you'll be able to use this style anytime you want, just going to the styles tab (Window > Styles).
With the eraser tool, erase the borders of your elipses so they look more like water falling. And it's finished!
Hover over to see "before" image.
I hope that you enjoyed this tutorial.
More Tutorials: 
