When using the default settings, the Lumia 2520 will automatically download and install any important updates.
If you would like to manually check for and install any updates, then simply:
- Swipe in from the right to open the charms.
- Tap Settings.
- Tap Change PC settings > Update and recovery.
- In the Windows Update page, tap Check now.
Once the checking for any updates is completed, you may view the list by clicking View details and manually select updates to be installed.