Could someone briefly explain the easiest way to go about starting my own affiliate program for a product or website I am or have already started?
Clickbank is widely used for that purpose. Why create something from scratch if it already exist and have a wide base of (possible) promoters already.
You can check out Idev affiliate software cost $99. You can also set up an affiliate program for your products with 2CO, Clickbank, JVzoo, paydotcom, and I'm sure there are many more!
A lot of affiliate programs that appear to be the websites own are actually managed with a third party application.
If you are thinking of how to integrate it into your site and manage it then there are good affiliate plugin for that if you are using wordpress. In this case, it will be yours and not clickbank or anyone's else.
you can start affilaite program on small scale by geting affilation from individual comapnies and then assemble them on one platform but you need resources in term of human and finance to promote your affilate program because you need make right mix between advertiser and publisher to satisfy both parties is tricky game.Best thing is work with already established companies.