How can I add basement and second floor to my project of building in Revit Architecture 2008?

can you give a little bit more information as to what your designing

There is no problem now.  I've found the solution. I've just added another level to the project and moved it under 0 level. I couldn't find the level button at first.

sometimes when your new to Revit this happens even after 6 years using Revit I have to think

Nice to hear it. That's mean that program is not always logical, I think.

where is the level button located in revit

Hope this still works: To create a new level, select the Basics tab on the Design bar and click the Level button.
If not maybe this link will help:
http://docs.autodesk.com/REVIT/2010/ENU/Revit%20Architecture%202010%20Users%20Guide/RAC/index.html?url=WS73099cc142f487551a875e110fcd770352-7aca.htm,topicNumber=d0e113753John Connor2011-03-01 18:20:18

Which revit do you have?

Have you tried looking in your Help file or User's Guide by any chance?
 
Try this:
 
Change > Properties > ElevJohn Connor2011-03-02 15:06:03

architecture 2011

[QUOTE=keizzer4567]architecture 2011[/QUOTE]And the question you're answering is...?  Or are you asking a question?

If you have any problem still to planning then you should hire a experienced contractor to solve ur probs......Stephanie Lewis2011-08-02 14:31:01

A contractor will not solve his problem as the "project" he is referring to is with the software being used (i.e. - Revit).