Sorry for the amateur qs, but been out the game for a bit. Trying to fix some ground issues and going over my starter I noticed a cable going from battery negative another from positive to seems like a fuse then to starter. Qs is can I just plug this up to the battery or where does this suppose to go?? Thanks in advance. This is the plug it leads to...... The right red one..

 

not sure why you have 2 powers to the starter?

Starter needs, power (the big terminal on the left) and trigger (from the ignition barrel), the grounding is done through its body (to the gearbox and engine).
I have a ground strap installed on one of the starter mounting bolts to help the grounding

 

If that wire attaches to the "big one" somehow,then it is automatically getting powered by the battery.That big wire is POS and always LIVE.
As Havoc said though..there is another wire that "triggers" the starter.It goes to what they refer to,outside of Australia(Sorry Havoc..lol..had to!) as the Solenoid.
Solenoid gets powered by the ignition switch at the start position.It kicks the Starter gear to the Flywheel and rolls the engine over.