what is a good css and html ide for ubuntu

If you really con't live without an ide (I prefer to work simply with a text editor) you can install Kompozer

sudo apt-get install kompozer

eclipse does not support html

or xhtml
 

Yes it does.

Assuming you're using Ganymede in the Help menu choose Software Updates.
Then in the available software tab choose Ganymede Update Site -> Web and Java EE Development -> Web Developer Tools and Web Page Editor

If you are in Galileo then I would assume they are in a similar position under the Galileo Update Site.

Eclipse is a huge program which allows you to add on the pieces you need to suit the type of development you do.

I use Eclipse for ALL web sites I create, whether it's PHP, xHTML or even Flex.

I went to the site how would install eclipse on ubuntu
check theses links out

http://www.eclipse.org/gef/ 
http://www.eclipse.org/downloads/ 
http://amateras.sourceforge.jp/cgi-bin/fswiki_en/wiki.cgi?page=EclipseHTMLEditor
 

Go to http://www.eclipse.org/downloads/ and download the one that says Eclipse for PHP Developers.

Once you have that simply unpack the archive file you downloaded and then double click on eclipse in the directory. That should start it for you.

I also use those other language like java and c++
cant I get every thing

Yes you can. once you have the basic eclipse installed you can then go into the software updates section in the help menu and add in all the other components you need to support other languages.