Wiring a Car up from Head Unit

[ekaJ]

Im confused as to how this works. I know you cant wire the power and RCA cables on the same side.
How do I get the wires across the dash and how do I pull up the door sills?

Any other help would be good, thanks

 

[marky-f1]

Usually up the underneath of the dash with plastic ties take rubber out the door seals at bottom and u can get in to run wires then up under the back / side of the back seats
I try not to run any wires passing driver side where pedals r thu