avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
The programmer Uno that you have loaded ArduinoISP isn't communicating with the computer. try re-upoading that Uno again with ArduinoISP sketch and see if the error changes. otherwise check to see which serial port you are connected to.