To update your website, go to Dashboard > Settings > Updates. If there is a new version available, you will see an update button. Click on the button to update your website.
If you sure that there is a new version available but you don’t see the update button, you can try to check for updates manually. To do that, click on the “Check for Updates” button.
After you updating your website, you may also need to update your theme. To update your theme, go to Dashboard > Appearance > Themes. If there is a new version available, you will see an update button. Click on the button to update your theme.