Line by Line? Do you have any idea how much work that involves?
It means writing a minimum of one sentence per line of code, and some of those lines will require a paragraph or so to explain them fully.
Try describing how to make a cup of tea in that much detail, and it will have gone cold (and probably mouldy) by the time you are finished!
Try and explain what your problem areas are instead, and we may be able to help.
"yes my ques is y we put dataaccess and if(Request.Files.Count != 0) this line plz explain...."
if(Request.Files.Count != 0)
If you don't understand something and it has '.' characters in it, then break it down and look at MSDN with google:
Request
is an object which retrieves the values that the client browser passed to the server:
MSDN[
^]
So Request.Files is an HttpRequest (which is what Request is an instance of) property :
MSDN[
^]
And Count is a standard property of all Collections, which tells you how many items it contains.
So
Request.Files.Count
tells you how many files were uploaded.
If this number is not zero, then execute the code block immediately below.
(Do you see now, how much work is involved in explaining an entire program, even one that small? :)