I really want to get Plex installed on my server but when I click plugins I get the following message "No entry has been found" and no plugins display.
Could someone please help me resolve this problem.
That's a pretty old version of FreeNAS and it doesn't look like a plex plugin is available for that version: http://download.freenas.org/9.1.1/RELEASE/x64/plugins/. You could try manually installing a plugin you downloaded from http://download.freenas.org/plugins/9/x64/ (follow the instructions in the PDF for your version of FreeNAS). Might be better off upgrading/reinstalling to the 9.2.1.x series.
That's a pretty old version of FreeNAS and it doesn't look like a plex plugin is available for that version: http://download.freenas.org/9.1.1/RELEASE/x64/plugins/. You could try manually installing a plugin you downloaded from http://download.freenas.org/plugins/9/x64/ (follow the instructions in the PDF for your version of FreeNAS). Might be better off upgrading/reinstalling to the 9.2.1.x series.