i am new to the program and i am building a 2 story house with a basement.  i can't find the add a floor button. can anyone help me

You don't mention what version of Revit you are using.  Have you tried looking under the Home tab?  Click on the Floor button and use any one of the drawing options.
 
Check out some of the tutorials I found here.
http://architecture.udmercy.edu/index.php/resources/autodesk-revit-tutorials/298-revit-flooring-tutorialJohn Connor2011-02-24 17:48:18

i can add a floor just fine, but i want it to be it's own level that i can make a floor plan of.  i have revit 2011.

None of the tutorials addressed how to change a floor's elevation in Revit?