How to make a radar mod?

I'm thinking of making a basic radar mod, something like the radar functions that most minimap mods have, but standalone. I'm completely new to making mods, so I'm not really sure where to even start.

I wasn't able to find any helpful information on making a minimap or radar mod, either with MCreator or other means, so I've got a feeling such a mod is pretty complicated to make. If someone could point me in the right direction of what I'll need to learn in order to start making one, it would be very much appreciated.

Thanks.