Step 4: Create New File in the Gimp
Now we'll create a 48x48 pixel image in the Gimp. While in the Gimp, ctrl+n for a new document, type in 48x48 in the Width and Height boxes. You'll end up with a blank square. Use Ctrl+V to paste the area selected in the previous step. You'll end up with a tiny bit of your original picture. Save the resulting image as icon.png.