Okay so:
1.) Open up Paint.NET. (Obviously. )
2.) Open a new file. To start, 800 by 600 pixels is good
3.) Add a new layer.
4.) Paste your picture onto the "layer."
NOTE~ If you put it on the background it will NOT work!
5.) "Crop to selection."
6.) Take the "magic wand."
It's located in the tool section:
7.) Put the "tolerance" to 37% to 41%.
NOTE~ This works best when the background is mostly one color and doesn't match your clothes.
8.) Hit "delete" on your keyboard.
9.) Delete the background layer. You can do this by going to the layers box, clicking on "background," and clicking on the red X
If it turned out like this, you did it right:
10.) Save it to a png file.
Just click OK:
And vuala! You now have a transparent avvie that you can leave the way it is or do something else with it.