I've been interested in discussions I see about API but have to admit I'm a complete noob in this area! I can see how to create a key in my account, but then the article says to enter this into the box provided on the third-party site. This is where I'm immediately lost - I have no idea how to find a site or what I could get it to do for me. I've seen the Wiki whch is linked from one of the GW2 Forums (https://wiki.guildwars2.com/wiki/API:Main#Services) but this goes over my head.
Please can anyone point me in the direction of a very easy idiot's guide to getting started with API?