It sounds as if you’re trying to install the wordpress discourse plugin in order to [quote=“Rajesh_Choudhary, post:1, topic:58816”]
add this kind of forum in my wordpress site
[/quote]
That’s not what the plugin does. Discourse is a separate application which (in most scenarios) runs on a separate server (see the install guide). The wordpress plugin allows a wordpress website and a Discourse forum to be interlinked, but you need to setup discourse first.