what does this error mean (avrdude: stk500_getsync(): not in sync: resp=0x00)

ApacheOmega:
I have to figure out which of my USB ports is the actual COM3 (I have 5 USP ports) how do I find out which one is COM3 pointed at?

That's not how it works. Things plugged into USB ports become COM ports; USB ports themselves, are not COM ports.