The Magic Wand Tool selects similarly colored areas. ^(x)

1. Choose the picture you want to extract the background.

2. Go to you PS tools and select Magic Wand Tool.

3.1 Open a new canvas.

File >> New >> Adjust the size of your canvas based on your preference and make sure that the background contents is TRANSPARENT.

3.2 Drag your picture to your new blank canvas.

4. Select the area you want to delete and press DEL on your keyboard. Repeat this step until you guys are satisfied with the removal of the background. 

5. The result. 

6. However, for my own opinion, using magic wand to extract the image from it's background are for lazy people, because it's very easy - like you're eating an apple. Here's an example, if you zoom the pictures, you'll notice some crooks and flaw at the output image.

So if you want a smooth and sort of perfect way to remove the background from the main subject of the image, you have to check out chapter 15 or the next tutorial.