You can check to see if an update is available in two places.
First, a notification will appear on your node dashboard that looks like this:
Or, you can check the Settings page of your node for this button, which will only appear when an update is available:
Running the update
1. Click either the notification on the dashboard or the Update button in your Settings page.
2. Enter your password and click Confirm to run the update.
Your node will take 5-10 minutes to complete the update. Once it's finished, you'll see the sign in screen again. Log in to unlock the node, and you're good to go!
You can double check this by clicking "Settings" in the System window of you dashboard. If an update is available, it would also appear there.
You can check your software version number in that same window, by scrolling to the bottom under "versions," as shown below: