According to this link above, you can click on the Upload Add-on link at the top right side of the page of Manage Add-on. Well that "Upload Add-on" link does not exist!
If you want to add plugins, you need a host who will allow it. OnDemand does not. There are a number of Atlassian Expert Partners who do hosting, and they have varying rules on plugins, costs and so-on. You can also install it yourself and run it on your own hardware, which means you've got complete control.
If you are thinking of changing who hosts your system, one small piece of advice - stick to people who explicitly host Atlassian systems, or are happy to let you have almost total control over the server. Quite a lot of providers who host services don't get involved in understanding the software, and prevent you from setting it up in a useful way.
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
We're bringing product updates and pro tips on teamwork to ten cities around the world.Save your spot