I can not upload images

Hello,
I do not know if I will be able to solve the problem, even if someone helps me. I do not much about computers.
I can not upload images in my webpage. When I tryed this is what happens.
“Unable to create directory /var/www/vhosts/arriagaarte.com/httpdocs/berriak/wp-content/uploads/2008. Is /var/www/vhosts/arriagaarte.com/httpdocs/berriak/wp-content/uploads writable?

Thank you