title: Need help trying to make Cmake find third party libraries
body: <p>I currently have a project that links to two third party libraries. These libraries have to be built by themselves and then linked to the project. One is taglib and the other is zlib. I noticed that when you use the Cmake-gui program on the taglib directory you're required to specify where zlib has been built and installed.</p>
  
  <p>My goal is to get CMake to do a similar thing for my program. Since the place these libraries are stored will be inconsistent how can I prompt the user to provide the path to the libraries required?</p>
  
  <p>I hope this is specific enough.</p>