How to change iPhone Wallpaper

Here are the easy steps you can take to change iPhone Wallpaper easily.
Make preparations:
Step 1: Find an image that you would like to use as wallpaper from iPhone Wallpaper
Step 2: Right-click on a PC or control-click on an Apple computer and select "Save As" to save the image to your computer. Save it to your "My Pictures" folder or iPhoto library on a PC or Apple respectively, or wherever you prefer to store your images on your computer as long as you will be able to easily locate it.
Step 3: Connect the iPhone to your computer with the USB cable and wait for iTunes to launch itself automatically. Click on the "Photos" tab in the side panel.
Step 4: Click on the "Sync Photos From:" tab in the "Photos" menu on iTunes and locate the folder where your photos are stored. Select all of the images that you would like to transfer your to iPhone. Click on "Sync" in iTunes to transfer all of the photos to your iPhone.
Change iPhone Wallpaper
Step 1: Tap Settings on the iPhone’s home screen:

Step 2: Tap the Wallpaper tab:

Several tabs should appear, including one that says Wallpaper. You can tap any of the tabs to select wallpaper for the iPhone. The Wallpaper tab features a collection of pictures supplied by Apple. The other tabs feature pictures you have added to the iPhone, including those taken with the iPhone’s camera.

Step 3: Tap any picture. A preview screen of the wallpaper will appear, along with the words Move and Scale at the top. You can pinch and reverse pinch the picture to resize. The transparent bars at the top and bottom simulate the bars for the clock and Slide to unlock that will eventually display on top of your wallpaper.
In the example below you can see that the heads of the two peoples will be partially covered by the top bar:

To fix, I will reverse pinch to expand the picture, then drag the picture so that their faces appear in the center:

Step 4: Tap Set Wallpaper to finish.
To view your new iPhone wallpaper, put the iPhone to sleep by pressing the sleep button on the top of the iPhone. Then hit the home button to wake the iPhone, and you should see the wallpaper.
Note the position of the clock and Slide to unlock transparent bars. If you’re unhappy with the position of the wallpaper, repeat the steps above.