Changing Icons

I've downloaded a couple icons Goodies « chris.ivarson for example to get a custom icon on my google calender and for the life of me I can't figure out how to use it. I go to get info an try to just drag it to the get info screen for my app but instead I just get a generic icon graphic. I'm clearly missing something here.
Help
PS I'm a total noob -been at the mac less than 24 hrs now

click on the new image, then copy (command-c)

open Get Info of the old icon and click the icon at the top, then paste (command-v)

toMACsh said:

click on the new image, then copy (command-c)

open Get Info of the old icon and click the icon at the top, then paste (command-v)

Click to expand...

Sorry to be dense -but in what application am I doing the copy? I click on it in Finder and past but I still just get this generic ICNS image.
File:icns.png - Wikipedia, the free encyclopedia

Ahh I found it posted somewhere

I was just able to copy and paste icons from any of the three file types
(.png, .ico, and .icns) by opening them in Preview, using Select All,
then copying and pasting into Get Info.

Click to expand...