How can I add Meta tag in my forum? (For SEO Purpose). Plus i cant find header.php to add this meta. Since i am new to this field . Please explain me in detail how to do it?
You can add your meta tags in the default.master.tpl of your theme. So go to: themes->views->default.master.tpl and add your meta's in the head tag
By the way: to increase your SEO, there is also a plugin available: http://vanillaforums.org/addon/vanillaseo-plugin
And to add your favicon, please use this plugin: http://vanillaforums.org/addon/favicon-plugin