Launching Screen Saver Settings
Click the start (Windows) button in the bottom-left hand of the screen, then start typing "saver password." This will show a result for Set screen saver password that you can click to launch:
Requiring Password and Screen Saver Start Time
Once the Screen Saver Settings panel loads, ensure the following are set:
"On resume, display logon screen" is checked
Set the Wait time to the recommended 5 minutes
Click OK when you're finished.
Manually Locking Your Computer
You can lock your computer at any time by holding down the Windows key, then pressing the "L" key.