It's not hard to do but the steps vary depending on the type of server and how it's configured.
Basically you want to redirect:
http://www.zhpmafia.com/amazon
to amazon's homepage but with the site's affiliate code attached to the URL
I can see the site uses apache so the best place to do this is in the http.conf file, but a lot of hosts don't let you access that. Next best is via the .htaccess file but again, some hosts don't allow this. Last would be an HTML refresh tag.