How to Backup iPhone File to My Computer?

There are too many files in my iPhone, so I want to backup them to my computer for saving storing space. But I can't do it. Why? Would you please tell me how to do?

You can either install iTunes on your computer or use iCloud.see http://support.apple.com/.../kb/HT1766

I would recommend the iTunes method, iCloud has limited free storage.

ITunes installed in you PC can create backups of your iOS device when you:
1. Sync with iTunes (disabled if you have iCloud backup turned on)
2. Right-click (or Control-click) the iOS device in iTunes under Devices and choose Back Up

Use these steps to manually back up your iOS device using iTunes:
1. Connect your iOS device to a computer with the latest version of iTunes installed
2. Select your iOS device in iTunes under Devices
3. Right-click (or Control-click) the device and select Back Up

iOS device backups preserve your settings, the Camera Roll (or Saved Pictures), and other important data.

Windows XP stores all of your iPhone backup files in this location:-

C:\Documents and Settings\user\Application Data\Apple Computer\MobileSync\Backup

Windows Vista and Windows 7 backs up the iPhone files to here:-

C:\Users\user\AppData\Roaming\Apple Computer\MobileSync\Backup