...also, do browse this forum. There are is a 'sticky' topic at the top of the list on getting started with the devkit:
http://archicad-talk.graphisoft.com/viewtopic.php?t=2699
and there have been other new users asking questions over the years. Those threads and the docs may help you get started.
The key is to study each example provided with the kit to understand the structure and interface of cross-platform add-ons.
Karl
One of the forum moderators • AC 25 USA and earlier • MacOS 11.6.6, iMac Pro