Addon for Picamera (video)

I would like to basically make a dash cam. I would like to have an addon that is maybe gui based if possible. I installed everything found here:
https://www.raspberrypi.org/documentatio…/README.md

Considering I have never built an add-on before, could you guys help me please? I want it to be enabled when the pi is on, and maybe record 4gb then overwrite it after 4gb is reached. Huh