You can add some visual flair to the lock screen in Windows 8.1 by displaying a slide show of images instead of just a single static image.
To set this up,
1- launch the Charms bar,
2- click on the Settings charm, and then select the option to "Change PC settings."
3- In the PC Settings screen, select the section for "PC & devices." The section for "Lock screen" appears on this screen automatically, as it’s the first item in the list to the left, as you can see above.
4- Turn on the option to "Play a slide show on the lock screen."
(Under that option, you can also choose whether to play the slide show when using battery power, if you're tweaking this setting on a laptop.)
5- Then, in the “Use pictures from” section, click on the link to "Add a folder" to select the folder with the images you want to appear in the slide show. The most obvious choice is your local Pictures folder, but you can choose other locations brimming with images, even your SkyDrive online storage. After you’ve opened your preferred location,
6- click on the button to "Choose this folder" and then select OK.
(You can add more than one folder, if you wish.)
( You can also click on a folder and select Remove to kick it out of the slide show.)
7- Reboot Windows, and you can now watch your slide show play at the lock screen.
