In other words, this site is pretty safe...
The easiest way is to do it using the "Get Info" of the finder on the file you want to change the icon for.
In other words, while having the file selected in the finder you click on command-I to bring the info panel.
In the upper left of the panel you will see the icon, the cool thing is that you can click on it and copy/paste from one file to another.
For example, if there is a picture I want to use for an Icon, I will first make sure its icon uses the picture, bring its Info and copy/paste it to the other file.
Enjoy. And let us know how it goes.