How can i add comments for every post?

Using JavaScript, you can achieve the same goal.

Please refer following link Comments[^]

Hi,

This is a sample of what you want to do.
It will definitely help you.

Forums Application Using MVC4 and Entity Framework[^]

Hi,

When you want to add a comment for certain existing data, then use logical solution to solve it easily.

If you are using some external third party controls the Grid view itself will have such option, but here if you solve using logical concept, it’s quite easy.

When the Main contents are available, then store that main content in a Table [“tblMainContent”] and name it with unique ID.

When user clicks for add comments using Javascript or Jquery show a HTML popup window where user can enter the comments.
Store the Contents in a Sub-Table [“tblComments”] where the foreign key will be the ID of [“tblMainContent”].

When you display the data on the screen use a simple grid view to display the main contents and based on the Comments for main contents add the dynamic Text block in the Grid row for appropriate main contents.

If you are good in CSS then in Sub-Table [“tblComments”] maintain other Column which will maintain the level of the comments, so based on the Comment level you can set color, Style of Font and border al for the sub comments and if you fetch the data from comments table by descending order, you can display recent comments at top and old at bottom.

Note: If you use Grid View control, you have many advantage has design, optimized loading of your contents, pagination and many more.
Which can appear in grid view as shown sample.

   Main Content 1 
        Sub Comments 1
        Sub Comments 2
        Sub Comments 3  

Main Content 2        
        Sub Comments 1
        Sub Comments 2
        Sub Comments 3

Thanks!

Please refer following link "Discus Comment System"
http://wordpress.org/plugins/disqus-comment-system/screenshots/