Arduino and 2 MOSFETs
Try adding a delay into your loop. In your code pin 13 will toggle very rapidly, much too fast to see it. For example:

void loop() {
  digitalWrite(13,HIGH);  
  delay (1000);
  digitalWrite(13,LOW);
  delay (1000);
}




It doesn't look wired correctly. For an N-channel MOSFET the Source should go to ground, like this: