If I have got you correctly, you want to edit the columns in each row and will have a dropdown in Remarks column.
This is a bit different story what you have posted of JSON call to get data from Default2.aspx.
In "success", when you get the data, you need to fill up the data in some editable grid instead display in table tag what you did.
Check the urls, which you will find interesting,
Editable GridView in ASP.NET 2.0[
^]
http://aspnet-with-c-sharp.blogspot.in/2011/02/fully-editable-gridview-in-aspnet-2.html[
^]
Hope this helps.
cheers