Compiling problem with Sensirion

I use the following #includes:

#include <Sensirion.h>
#include <Wire.h>
#include <Arduino.h>
#include <WConstants.h>

I got these errors

C:\Users\Wim\Desktop\arduino-1.5.2\libraries\Sensirion\Sensirion.cpp:30:26: error: WConstants.h: No such file or directory
C:\Users\Wim\Desktop\arduino-1.5.2\libraries\Sensirion\Sensirion.cpp: In constructor 'Sensirion::Sensirion(uint8_t, uint8_t)':
C:\Users\Wim\Desktop\arduino-1.5.2\libraries\Sensirion\Sensirion.cpp:86: error: 'OUTPUT' was not declared in this scope
C:\Users\Wim\Desktop\arduino-1.5.2\libraries\Sensirion\Sensirion.cpp:86: error: 'pinMode' was not declared in this scope
C:\Users\Wim\Desktop\arduino-1.5.2\libraries\Sensirion\Sensirion.cpp: In member function 'uint8_t Sensirion::meas(uint8_t, uint16_t*, uint8_t)':
C:\Users\Wim\Desktop\arduino-1.5.2\libraries\Sensirion\Sensirion.cpp:147: error: 'delay' was not declared in this scope

And many more

What do I do wrong?

One thing that you have done wrong is not to post the whole code.
Another is to put the libraries in the wrong place. User installed libraries should go in the libraries folder of the folder where you sketches are stored.

I don't suppose that you've bothered to search for that error message on the forum. There are hundreds of hits.