Input files for the PWscf codes may be either written by hand (the good old way), or produced via the "PWgui" graphical interface by Anton Kokalj, included in the QUANTUM ESPRESSO distribution. See PWgui-x.y.z/INSTALL (where x.y.z is the version number) for more info on PWgui, or GUI/README if you are using CVS sources.
You may take the examples distributed with QUANTUM ESPRESSO as templates for writing your own input files: see section 2.3, "Run examples". In the following, whenever we mention "Example N", we refer to those. Input files are those in the results directories, with names ending in .in (they will appear after you have run the examples).
Note about exchange-correlation: the type of exchange-correlation used in the calculation is read from PP files. All PP's must have been generated using the same exchange-correlation.