The update cannot be installed because we will be unable to copy some file

I know very little about wordpress or websites generally. It is on an old version and provides this error trying to upgrade. Really I should farm this out to someone to sort it professionally. Any suggestions?

The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.: wp-admin/includes/update-core.php

Installation Failed

The page I need help with: [log in to see the link]