I am trying to change the background on some Aliases and folders I created on my desktop. I downloaded some icons in .ico and .png format online, and I am able to use the .png format. I open up the .png file, ctrl-c it, then goto the Alias or Folder I want to change the icon on. I do a "Get Info", then I click on the icon at the top and do a ctrl-v. This changes the icon, but it puts a White background behind the icon. See the screenshot below to see what I am talking about.
What am I doing wrong?
Screenshot of resulting icon on desktop
Site where I downloaded the icons
http://www.iconarchive.com/category/system/black-and-blue-icons-by-icondrawer.html
What am I doing wrong?
Screenshot of resulting icon on desktop

Site where I downloaded the icons
http://www.iconarchive.com/category/system/black-and-blue-icons-by-icondrawer.html