How to use Event Viewer in Windows:
Use Event Viewer in Windows®. To open Event Viewer follow the steps below:
1. Press 
+ R and type“eventvwr.msc” and press Enter or click OK.
Security note: If UAC is enabled, then you’ll get a UAC prompt on screen. Please specify credentials or permission to pass the UAC elevation.
2. Click Yes to give the Event Viewer permission to run.
3. Expand Windows Logs and select Security from the left side. You will see Application, Security, Setup, System and Forwarded Events.
4. In the middle of the Event Viewer you’ll see Number of events, and what has happened etc, whether it was a log-in or a logoff which was performed.