Melee Attack System

I have been learning to work with unity for a while now both C# and JavaScript but on my recent project the one thing I havent yet figured out is an attack system for my current project. All I need to get moving agin is an ttack system shown below also please dont just post a sctipt and be like "Here This Works" try to explain why it works how it works and what makes it work.

Health Script

var curHealth : int = 100; var maxHealth : int = 100;

 var healthtext : GUIText;
  
  
  
 function Start () {
  
  
 healthRegen();
  
 }
  
  
  
  
  
 function Update () {
  
  
 healthtext.text = curHealth + " / " + maxHealth;
  
  
 if(curHealth < 0 ) {
  
 curHealth = 0;
  
  
 }
  
  
 if(curHealth > 100) {
  
  
 curHealth = 100;
  
  
 }
  
  
  
 if(Input.GetKeyDown("e")) {
  
 curHealth += 10;
 ManaScript.curmana -= 20; 
 }
  
  
  
 }
  
  
  
  
 function healthRegen () {
  
  
 for(i=1;i>0;i++) {
  
  
  
 yield WaitForSeconds(1.5);
  
 if(curHealth < maxHealth) {
  
 curHealth++;
  
 }
  
  
 }
  
  
 }

Mana Script

 #pragma strict
     
 
     static var curmana : int = 100;
     var maxmana : int = 150;
      
     var manatext : GUIText;
      
      
     InvokeRepeating("manaRegen", 2, 5.0);
       
     function Start () {
      
     
      
     }
      
      
      
      
      
     function Update () {
      
      
     manatext.text = curmana + " / " + maxmana;
      
      
     if(curmana < 0 ) {
      
     curmana = 0;
      
      
     }
     
      
      
     if(curmana > 100) {
      
      
     curmana = 100;
      
      
     }
      
      
      
     if(Input.GetKeyDown("1")) {
      
     curmana -= 10;
      
     }
      
      
      
     }
      
      
      
      
     function manaRegen () {
      
     curmana += 5;
      
      
      
     }