I start with a 52x52 px page. I magnify to fit the window. I choose background options, and reduce Alpha channel to 0%. I create a design. Go to file>export bitmap. Now what?
I'm trying to replace my iMac icons with background-less self made ones. Please, someone walk me though the steps.

Save the file as a png. Select the png file in Finder. Choose Get Info from the File menu. Click the icon that appears in the Info window. Choose Copy from the Edit menu (Leave the Info window open). In the Finder, select the folder or document whose icon you want to change. Click the icon that appears in the Info window. Choose Paste from the Edit menu. That's it...

But the previews on my desktop have no background, when info is selected the top icon isn't the graphic it's a picture of a piece of paper with PNG on it.