If you download any PLUGINS or BEHAVIOUR here what you do.
1 open Construct 2 folder C:\program Files\Construct 2\exporters\html5\plugins
drag Plugins here or if it's Behaviour then
2 open Construct 2 folder C:\program Files\Construct 2\exporters\html5\Behaviours
or if it's Effects then do this paste in
open Construct 2 folder C:\program Files\Construct 2\effects