On internet you can find few codes. I think it wouldent be hard if you know programming to do your own code.
Well i actually do not really know programming
It depends on the current code of your site. 'Referral program' is not something you can add by copying and pasting some code. It's not difficult but it needs to be properly integrated into your site.
If you don't know how to program you should post on Services and hire someone to do it for you. Make sure to include the language of your site (ex: PHP) and whether it uses a CMS or a known script. You will need to explain to the coder the exact logic to reward referrers and referrals. I can help on this as long as it's not for a ponzi (or similar) site.
