Hi Carolina,
firstly welcome to the forum!
I'm sorry no one's answered your post.
I abandoned all but the most basic javascript because of security issues (and service pack 2), cross-browser issues, and it's not se friendly much of the time. I prefer to use plain html or asp now, but many use php. Tell us a bit more about the aims of your site, and we can make some general suggestions about how you should move forward - maybe save you some time!
I think you have a duff book! There are a few really good web resources with online tutorials or sites where you can copy and paste working solutions that you can modify.
Try this one first (for creating cookies):
http://www.js-examples.com/javascript/?view=665
Then this more advanced one for modifying cookies (but has documentation):
http://www.quirksmode.org/js/cookies.html
Also, sometimes the most simple code works ok in IE6, but doesn't in IE 5, Netscape/Mozilla (and vice versa) without some modification, so you should test your scripts with IE6, IE5, NS7, and
maybe NS 4.79.
Cheers,
Paz.