here is the difficult task in my program i overcome all the previous challenges with your supports (thanks to all of who supported me) but i reach to closed door , the page i want to scrape is showing loader bar for some time then it loads the HTML which has the link of the book i want to get it
how i can overcome this
That depends... If the loader bar is javascript (or similar) and the html doesn't get loaded if the javascript isn't executed, you can't just do a gethtml() to get the page.
So first check what your gethtml() function gets as text.
If in that text there is nothing you want to scrape... you'll need to execute the javascript. Maybe you can use the IE engine to get the file (which does execute the javascript).
For example you could use Browser := CreateOleObject('InternetExplorer.Application'); to initiate an internet explorer browser and with navigate, navigate to the correct page and read out the html.
(but that's only under Windows)
If there are any security measures (like Captchas), you'll still need to do some things manually.