Need help with 4 scripting errors

Need help with scripting errors. I'm creating a game for school, and I'm more of an animator. Its a 2D fighter.

1. Unity is stating void start is an error because of void. if I delete void, it still gives an error, if I delete the line I still get an error. Not sure what I'm doing wrong

// Use this for initialization

void Start()

     void Update()

     {
     AttackInput ();
     ScaleCheck();
     OnGroundCheck();
     Damage();
     UpdateAnimator();
     }

1. Unity is stating float is an error, if I remove float it creates jmpduration as error, and creates additional errors.

public float JumpForce = 20; public float jumpDuration = .1f float jmpduration float jmpforce; bool jumpKey; bool falling; bool onGround;

1. repeats same error above?

2. Unity states unexpected symbol {

public class DamageScript : MonoBehaviour { void OnTriggerEnter2D(Collider2d col) { if(col.transform.root != transform.root && col.tag != "Ground" && !col.isTrigger) { < MARKED UNEXPECTED if(!col.transform.GetComponent().damage { col.transform.GetComponent().damage = true;

                 col.transform.root.GetComponentInChildren<Animator>().SetTrigger("Damage");
             }
         
             }
             }
         

Can anyone help me fix these?