[Kile-devel] Does not find amsmath.sty package

[Mehdi R. <e1...@me...>]

Dear Sir or Madam
I have recently installed Kile 1.9.1 on ubuntu 6.10
When I use the command "\usepackage {amsmath}" it says that it can not 
find this package. How can I install new packages?

Thanks
Mehdi