LM393 IR Speed Sensor

So I want to measure the speed of a small fan moving as per how hard I blow at it using the LM393 IR Speed Sensor. How do I code for that?

Start with the following and fill in the function bodies:

void setup() {
  // put your setup code here, to run once:

}

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

}

Googling "arduino LM393" will provide some information relevant to the process.

The LM393 is a comparator, not an speed sensor. Anyway, why don't you go read the sticky and post a good question? It'll go a long way in getting the help you're after.