WHDLoad works with *original* disks only (very few installers work with cracks).
A WHDLoad installer is a simple installscript using the Amiga's standard installer GUI. Simply download the appropriate installer from
http://www.whdload.de, depack the archive and start the installer by doubleclicking its icon.
You will be guided through the installation process ("insert floppy disk 1 now" etc.), it's not exactly rocket science ;-)
The process is more or less the same for all games.