It depends how you downloaded it: as a.iso you will have to burn it directly to a CD (using fireburner) then run the setup.exe from there (hopefully it will have provided the serial number). It may be as a .zip/.exe/.rar (.r01 etc) in which case you must decompress the files to a central area (eg C:/office) using winzip, running the .exe or using winrar, respectively. Once you have all of the files, just use setup.exe. WARNING: always have a real-time antivirus program running since kazaa files are notorious for being virus infected.