Things You'll Need
Instructions
Open your "minecraft.jar" file using an archive utility launcher. Your "minecraft.jar" file will be located in your game files or application support. If you are not sure how to access this file on your particular operating system, preform a search on your computer.
Locate the folders in the "minecraft.jar" containing the specific texture files you want to modify. Examples of textures can include landscape texture files, item texture files and weather texture files. The texture files will be in the form of a PNG. You will be able to view the textures in each file as they are presented in the game. The folders in which these texture files are in will be labeled.
Save the PNG texture file to your computer and open it in an image editing program. Edit the PNG file by drawing on it or erasing the pixels. Save the file you edit with the original name.
Replace the file in the "minecraft.jar" with the file you edited. Click "Replace" when prompted.
Play Minecraft. Open up one of your world saves to view the changes you made to the textures. Re-edit the texture files by following steps 1 thru 4 as needed.