(JS)WaitForSeconds Within Update

So i have a JavaScript here, it's for a catapult, kinda like the one you can see in this trailer:

"Go to 2:12 to see what i mean". So my basic functions are, if i press "F", the catapult goes into a charging animation. And that calls a function called Charged, which waits for 10 seconds before it's charged.
When it's charged, i want it to be shootable with "p" after 10 seconds when it's charged.
I have tried soooo many ways. I have barely any idea how to script, i just mixed some stuff up
First of i can't put a if(Input.GetKeyDown("p")) in my custom functions, and i cannot put Yield WaitForSeconds(x);
in my update fuctions. There are probably good reasons for that, that i don't understand, but that's not the point though
Here is my messy unproffesional script:

1. #pragma strict
2. var node1 : Transform;
3. var Boulder : Transform;
4. 
   
5. function Update () {
6. if (Input.GetKeyDown("f"))
8. {
9. animation.CrossFade ("Charging");
10. Charged();
12. yield WaitForSeconds (12);
13. {
14. Debug.Log("Ready to Fire");
15. }
16. if (Input.GetKeyDown("p"))
17. {
18. Instantiate(Boulder,node1.transform.position,node1.transform.rotation);
19. animation.CrossFade("Firing");
20. }
21. 
    
22. 
    
23. }
24. }
25. 
    
26. 
    
27. function Charged() {
28. 
    
29. yield WaitForSeconds (9);
30. animation.CrossFade("Charged");
31. Debug.Log("Charged");
32. }

-Thank you for taking your time to read through the mess lol

 

Use code tags when posting code. You can't use yield in Update; only in coroutines.

--Eric

 

Yeah, but i don't know how i would do this, i don't know how to use coroutines properly, could you give me a tip?

 

http://docs.unity3d.com/Manual/Coroutines.html

--Eric