>>1491949Google
Paint.NET, it has a few more advanced options compared to your standard paint but isn't overly complicated like PS or Gimp.
I'd say you just need some edge work done and yours would be perfect, mind you that these are just fine already. Open the file and zoom in as close as you can stand (while still being able to differentiate colors and the picture as a whole) and take a single pixel width eraser tool and remove the colored pixels that are obviously not part of the main photo. If you are having problems seeing the colors add a separate (temporary) layer to the image and give it a strong contrasting color (such as dark red or blue) so that the image becomes more visable.
