I get this error on my site, http://endometrialcancer.org even though the folders are indeed there and chmodded to be server-writable. Could the problem be that the site is in the www folder rather than the public_html folder? My web host says no.
It doesn't look like you can use the file upload feature at this time because the directory you have specified (/home/endometr/public_html/wp-content) doesn't appear to be writable by WordPress. Check the permissions on the directory and for typos.