How to convert the background to transparent? [closed]

I would recommend this (just found via search):

1. http://lunapic.com/editor/?action=load
2. Browse for image to upload OR enter URL of the file (below the image)
   http://i.stack.imgur.com/2gQWg.png
3. Edit menu/Transparent (last one)
4. Click on the red area
5. Behold 🙂 below is your image, it’s just white triangle with transparency…
   [dragging the image around in your browser for visibility,
   the gray background and the border is not part of the image]
   
6. File menu/Save Image
   GIF/PNG/ICO image file formats support transparency, JPG doesn’t!