Topic: How to redirect the page?

If I open the page on my website http://xy/update.html it asks the password and opens http://xy/update/enterpin.html if the password is correct
But I can directly also open the page http://xy/update/enterpin.html
I want the page to redirect to http://xy/update.html if I open it directly and then open by entering the password only.
Please tell me how to do the task?

In Javascript?
Not at all.

I suggest you read up on basic http authentication - one of the few secure ways to password protect your pages.
(The alternative would be to use a server side language like PHP to authenticate the user and only output the content if the username & password matched - but since your files end in .html I guess that's not what you want)

so long,

->Tyberius Prime

This tutorial at the Gurus Network may come in handy -

http://www.gurusnetwork.com/tutorial/htaccess/