Yea, you'll need some javascript to change the visibility of the div. Go check out the prototype framework (http://prototype.conio.net/) or the moo.fx framework (http://moofx.mad4milk.net/) they'll be able to help you do what you want, and much more.
Thanks guys for the info, but why I'm being redirected to other forums and website while all I need is a simple login form shows and hides when clicking on a link?!
I maybe posted in the wrong section, sorry it's my fault. :)
You'll need to know a little bit of javascript to do what you need, but given the power and scalability of the thing you'll thank yourself for it :) I learnt everything I know through the Javascript Bible (5th edition) and just tinkering around, but there are plenty of web tutorials. BTW does anyone know the tool used to compress jQuery to under 10kb? Why aren't more people using it? Is the size <-> performance hit too great?
jskopek: jQuery is compressed using Dean Edward's Packer which compresses and obfuscates the code. The only catch is that you can only have one .js file compressed that way or they'll start to have conflicts because of the way it does it's stuff. (Though if you wanted to you could include the full source of jQuery into your .js library and then compress the whole deal again.)
Sam i think you want something like this: http://www.daddy.ro/contact.php (Don't read the text. This site is in Romanian) Clik on "formularul urmator" and a form will apear. The div with the form contain an "X" for closing the div. Look at the XHTML code and take the JScript from his location. P.S. Excuse my English, but is not my native language. So,enjoy with my JScript open-div method for forms. ;)