I have never worked with APIs before (and have very little programming experience outside of HTML and CSS) and I am struggling to find any clear tutorials or explanations. 

Do APIs all work in the same way? Can you use any programming language or only a specific language or does that depend on the API? Is there a common way to work with some of the major APIs? Do you know of any really basic API tutorials or do you really need to be au fait with particular coding languages before you start down that road?

There is no specific API that I "need" to work on but I would be interested to have a play with services such as Twitter, Flickr, Google Maps, Facebook, Last.fm, etc. if it's accessible.

Any advice would be much appreciated thanks,

Luke