You will need to use a server-side scripting language to do this--HTML/JavaScript/CSS can't do this alone. I would start with PHP--there are lots of tutorials on the internet and is available on most web hosts. But if you know Python, Perl, ASP .NET, Ruby on Rails, etc., those can also be used to do this.

You don't need a server side script for this. You can use JavaScript.

http://www.htmlgoodies.com/beyond/javasc...

This should give you an idea of what has to happen.

How can we implement this feature? For example, if a website has two text boxes for entering username and password, how can I enter this data automatically by using a file which will have the data?

so for suppose like yahoo sign in page, and I have a file which has such info:

username: dddd

password: fff

so some app should be there which uploads these values into the text box directly how?