Need help with wiring harness

Hey guys I need help again. So I never took this wiring harness out of the car. I know how to read a wiring diagram, it's not easy for me but I can do it, but my problem is where do the grounds for the engine go and things like the starter solenoid etc?

the starter relay grounds by bolting to the fenderwell.. the engine ground if there is one (my 70 never had one) usually goes from the back of the engine to a bolt on the firewall..