In Windows 7 Microsoft introduced Action Centre, which brings together important alerts about the security and maintenance of your PC that need your attention. The Action Centre uses a colour coding system that flags up significant issues that need to be addresses quickly in red while suggested issues that are viewed as slightly less important (but should not be ignored) are marked in yellow.
There are two ways to see if there are any issues that need your attention in the Action Centre. To begin with hover you mouse over the flag icon in the far right-hand corner of the task bar. A message will flash up with any notifications. Simply click the icon to see these alerts in full and then press Open Action Centre.
Alternatively, from the Start Menu open the Control Panel. Select the System and Security section and then chose Review your computer's status and resolve issues. A window will display all of the notifications highlighted in the relevant colour. Next to each of them will be an action depending upon the notification. For example, Windows Defender may be requesting to scan your computer so you'll see a Scan now button. Simply press this to commence the scan. Alternatively, you may now have any backup set up and Windows will notify you to check your backup settings.