I have downloaded the Contact_us plugin from the subrion website and extracted the zip file to my PC desktop. The various tutorials I have found tell me: "Upload all the files from unpacked 'plugin_name' directory to your subrion directory ../plugins/ folder." However, I believe this is obsolete as I cannot find a /plugins/ folder in the root of the site. The Plugin Manager on the Admin page does invite me to upload a small selection of plugins, but the Contact_us plugin is not amongst them. Please kindly advise.