error: a function-definition is not allowed here before '{' token

Hi there people, this is my first time using Arduino for a while, so forgive me if this is stupid.
I am getting the error message

a function-definition is not allowed here before '{' token

on line 3 of my project. It is on an Uno and it is a function to make a robot go forward.
Thanks for your help!

void setup() {
  // put your setup code here, to run once:
  void forward() { // Make robot go forward

    digitalWrite(9, HIGH);
    digitalWrite(6, HIGH);

  }
}

void loop() {
  // put your main code here, to run repeatedly:

}

You cannot define a function inside of a function.

Remove forward() from within setup().

Thanks! I will try