[NTG-context] Write your own module?

Hi, I'd like to start writing a module, and test it using ConTeXt MkIV standalone installation. Dived into wiki.contextgarden.net but was unable to find a basic tutorial on how to tackle this. Yes, I did find a module template, but can't figure out where the module should go such that ConTeXt can find and load it. Any hint would be very helpful. Thanks in advance! Regards, Gerard