How to build Api integration

Hi there,

i've been using creator for our standalone app in the past year. Now I would like to build an integration with local (Dutch) accounting software. They do have an API available, and I'd like to have Creator create a new customer when we do that in our accounting software, and vice versa. I'm not an API expert so was looking online but couldn't really find how to do this.
anyone that can point me in the right direction? eg online explanation etc.
I remember this was part of the developer training but don't see much info on the Creator help.

thanks,
boudewijn