What this tutorial will do: Tell you how to modify an existing Sims 3 skin to add a penis texture.
What this tutorial will NOT do: Give detailed instructions in how to use an image editor. It's assumed you know how to select an area in an image and do a copy and paste. It will also not tell you how to install the software you need or how to resolve problems running it.
THIS TUTORIAL IS INTENDED FOR YOU TO MODIFY SKINS FOR PERSONAL USE. IF YOU WANT TO ADD PENIS TEXTURES TO A SKIN BY ANOTHER CREATOR AND UPLOAD IT, YOU MUST GET PERMISSION FROM THAT CREATOR.