Windows 8 shows a default lock screen picture which you can easily change with your favorite picture. Using Personalize feature in control panel you can change both, lock screen picture and your profile picture in Windows 8.
Tip: If you are using password to login windows 8 then you will see the same image on logon screen. So this same picture will be shown at both place.
First of all, click on the profile picture at right top of the start screen as shown in the following screenshot and select “change user tile” option from dropdown.
Once you have selected user tile option then it will open control panel with personalize settings.
Click on “Lock screen” option just below the personalize heading. See the above screenshot. Then it will open “lock screen” setting page where you can change the picture. Either you can select from the given lock screen pictures or you can upload a new picture using browse button.
That’s it ! Finally you have changed the lock screen picture in your windows 8 operating system. Now, you can check out these Windows 8 Shortcut keys. BTW, if you are still waiting for windows 8 then download the windows 8 developer preview and check out the windows 8 screenshots.