Quote from Zuriki »Open minecraft.jar using WinRAR
Copy the terrain.png file to wherever.
Put back into the JAR using WinRAR
Go to www.minecraft.net and run the game on SP (MP works as well)
Quote from Zuriki »minecraft.jar NOT minecraft-server.jar
On windows XP:
"C:/Documents and Settings//Local Settings/Temp/www.minecraft.net/"
Quote from Zuriki »Remember if you edit the the JAR in: minecraft.net
Then you have to go to http://minecraft.net
If you edit the JAR in: www.minecraft.net
Then you have to go to http://www.minecraft.net
Also, you have to put the terrain.png back into the JAR file after you edit it.