After searching the web so much , reading a lot about css , i found two tut’s very effective .
Ok you should read a Css manual like http://www.tizag.com/cssT/ or http://charlescooke.me.uk/web/uga_css.html , and basic html knowledge.
but these tut’s are really effective:
http://wysif.onlinewebshop.net/gary777css.html
http://www.gregtutor.plus.com/kompozer/layerdemo.html
all the ones from kompozer from gregtutor are really usefull.