title: How to include external libraries in Qt
body: <p>I want some basic explanation about how external libraries are added to a Qt C++ project in a Linux environment
  I've installed a library called podofo in two ways : 
  - Installed it with apt-get install libpodofo
  - Installed the source code and build it</p>
  
  <p>Afterwards i added in the .pro file of my Qt Project : LIBS += -lpodofo</p>
  
  <p>How do i choose whether he works with the first or the second one ? 
  How am i supposed to add an external library with a lot of .jar files in my project ? </p>
  
  <p>I figured it might be something in the run environment but i still don't get it. I tried changing it but it seemed better to just copy libraries manually in the file Qt is installed in.</p>