I wonder is there any way we can create regions in aspx page as we create it in our cs pages.
not as Expandable, but in HTML it is normal to use the comments in order to create blocks of code
<!-- Start: Login access form -->
... Code ...
<!-- End: Login access form -->
I don't think there's a way to do this.
However, I would suggest that if you are feeling the need to do this because your .aspx pages are very large, you might should look at redesigning it, or breaking it apart into User Controls (.ascx) or figure out a more effective use of master pages.
Not sure if that's the reason behind your question, but if it is, it's just a thought to pass on.
Visual Studio does a pretty good job of identifying elements with a significant amount of content to make it collapsable dynamically but thats the closest you going to get.
It might occur to you to place a series of element sibling in a DIV so that the div can be collapsed in visual studio. Thats very tempting but I would advise against it.
Regions are an IDE convenience that allow you to name a segment of code that may span multiple functions or procedures and be able to collapse/expand the whole segment as a whole. Visual Studio provides this feature only for code and not for HTML/ASPX/CSS portions of a file. For instance, you can create Regions within the <script runat="server"> section of an ASPX file.