Well what is a Minecraft world? A Minecraft world is a build you can download.
Step 1: Download a World
We will use a world form my website: http://randomcow.sokolovfamily.com/How.zip
Step 3: Where Do You Put It?
first go to start then go to %appdata% then Roaming then .minecraft
Step 4: Where Do You Put It?
You will see the folder saves so open it and put what you extracted and search for the world in minecraft! Your Done!