Hi, this is ultimate and easiest guide to mine Monero.
Even old PC's with 4 core Intel i5 and without some fancy nVidia or Radeon GPU can make 30-40$ a month while burning just 5$ extra in electricity.
Enjoy reading and mining.
 
https://multicoin.joomla.com/11-only-profitable-cpu-mining-monero

If you are lazy to read but experienced with mining, you can skip directly to Windows 64-bit xmr-stak on repository:
http://mirrorupdate.com/repository/XMR-stak/v2.0/XMR-STAK_CPU_GPU_miner.exe