Designing comments with reply option (nested structure)

I haveto design a page which will have different posts and an option to post new one every post has commnents and comment box to post a new comment ,every comment should have a reply option .so that i have to display all the comments in a nested structure.

I am able to display the posts and their corresponding comments but unable to display the comments in a nested structure and how can i implement reply option for every comment corresponding to a post.

please help me in implementing the above

be positive.............