Be sure to dilate your skin after it's finished, it'll clean up extra transparent pixels around the edges of the skin. You can dilate by navigating to the folder that contains your ddnet.exe file, and simply dropping your skin on the dilate.exe file within the same folder.
@@kalechips3403 go to skin tab in ddnet settings and click on the folder icon. It'll open the folder where you can put your .png file. Then click on the refresh icon in skin tab and search for your skin or type its name