Bhavika Rugnath, Oxwall support doesn't include providing instructions on custom code modifications.
You can suggest this feature to UserVoice (http://oxwall.uservoice.com/forums/13756-ideas-for-oxwall). Or find a developer to complete this work for you.
Note that Oxwall comes with build in "Flag" feature. Any user can flag content like blogs, links and etc. Flaged items get displayed in admin's dashboard and he can take needed actions.