Things You'll Need
Instructions
Right-click on the name of your new "Minecraft" skin and select "Rename." Change the file name to "char.png."
Open Windows Explorer on your PC and navigate to the "C:\Users\[yournamehere]\AppData\Roaming\.minecraft\bin," replacing [yournamehere] with the name of the user account where you have "Minecraft" installed on your PC.
Right-click the "minecraft.jar" file and select "Open With." Choose the unzipping tool, such as WinZip or WinRar, you have installed on your PC.
Copy and paste the "char.png" file into the Minecraft folder that opens. Select "OK" on the prompt that appears. You have now applied a new "Minecraft" skin in a downloaded game.