How to add new units to a mod in OpenRA?

[uprootannoy]

Hello everyone in the OpenRA forum!
I am currently learning how to edit and create my own mod for the OpenRA game, but there are still many things that are unclear. I would like to ask if there is any detailed guide on how to add a new unit (such as a tank or soldier) to the game? I tried editing the rules.yaml file but when I enter the game, the new unit does not appear. I am also not sure if I need to edit any other files. If anyone has experience or knows any easy-to-understand documents, I hope to help. Thank you everyone in advance!