Minecraft Paint.net?

When I wanted to create a texture pack with Paint.net, I also managed to replace the texture, but my new texture in the texture pack has such a white border. So I made a sword, but the remaining pixels from the picture that I didn't use were replaced by a white surface, and not left out! So now I only have one picture with a sword on it, but which has the same capabilities as a diamond sword! And I saved it as a .png file.

Can you help me?

You have to make all the pixels that you don't want transparent.

How do you do that?

Set opacity / transparency to 0. Then you can simply replace the white pixels in the example and then you have transparent pixels.

OK thanks!