There are three ways to install plugins in Fogbugz
For FogBugz On Demand accounts, the only way to install new plugins is via the Plugin Gallery. Because FogBugz On Demand is a shared environment, only plugins which have been approved by Fog Creek can be enabled. You cannot upload your own. This is to maintain the highest quality of service and protect your account from malicious or poorly-written code.
Once installed, plugins are configured via the "Configure" icon next to their names on the Plugin admin page. The icon only appears next to plugins that have configurable options.
Plugins can be deleted from FogBugz by administrators on the plugins admin page by clicking Plugins from the Admin menu. Click the "delete" icon next to the desired plugin to completely remove the plugin and all associated data. If you wish to preserve plugin data, disable it instead by clicking clicking the "yes" or "no" link in the Enabled column.
When a new version of a Plugin is released, you should not delete it in FogBugz before installing the new version. Doing so will cause you to lose all data and configuration for the plugin.