Yes, that sounds like a permissions problem. Does it say something like this:
Install add-ons from the Moodle plugins directory
There is a request to install add-on Sitewide User report (gradereport_sitewideuser) version 2013092100 from the Moodle Plugins directory on this site. However, the plugin type location /var/www/html/grade/report is not writable. You need to give write access for the web server user to the plugin type location, then press the continue button to repeat the check.
If so, do you have access to the SSH for your server? Otherwise contact your server/hosting service to change the file permissions on all the folders listed as plugin types on that Install add-ons page:
And yes, you can't be IT ignorant to deal with Moodle application files, you either need to learn about PHP/MySQL web applications for yourself or hire a Moodle Partner to take care of your installation. Don't despair, the moodle community is rich with helpful people and free resources.