I wrote my original post in a rush, and hadn't appreciated how ambiguous it was until I got the variety of replies that I did
I'm not very internet-savvy, but I was trying to investigate how one goes about becoming an affiliate for on-line retailers, thereby earning commission. I know there are lots of people out there marketing affiliate training courses....they'll say "give us shed-loads of money, and we will show you how to make shed-loads yourself", but that all seems like another greed-fuelled bubble to me. I am sure that there are easier, and cheaper, ways of making ...if not shed-loads.... small cloakroom-loads of extra cash.
Tell me if I've missed the boat. I'm just counting my tulips now.....
Affiliate marketing is massively competitive so unless you are pretty tech savvy its unlikely you will make much money from it. Industries like travel and gambling have literally thousands of affiliate sites and driving people to your site (and then capturing the affiliate cookie) is very difficult. If you have an understanding of web site construction and SEO then you can make money but without that i'd suggest your costs to build the site and pay for online marketing will be less than what you make.
If you are looking to make money online you are probably better looking at matched betting. You are guaranteed to make money from that but it does take time and effort.