Timer triggered instantiating

Hello,

I am scripting spawning meteors every x seconds in a random range in front of player, i am getting errors tough, also this only spawns one meteor, i would like to spawn more meteors as time passes, i think about adding multiple timers for spawning, or maybe play with spawn method to create more than one meteor.

I would appreciate any help to fix errors and also some way to achieve multiple spawning meteors.

Thanks in advance.

Errors are :
1- 13,12 unexpectedsymbol void
2- 27,23 unexpectedsymbol private
3- 27,23 unexpectedsymbol private
4- 27,23 unexpectedsymbol private
5- 30,134 unexpectedsymbol quaternion

using UnityEngine;
using System.Collections;

public class Meteorbomb : MonoBehaviour {

	public Transform prefab; 

	public float myTimer = 15.0
	
	
	
	// Update is called once per frame
	void Update () {

		

			if(myTimer > 0){
				myTimer -= Time.deltaTime;
			}
			if(myTimer <= 0){
				Spawn () ;
			mytimer = 15 ;}
		}


	void Spawn(){
		private int x1 = Random.Range(-6.0F, 13.0F);
		private int y1 = Random.Range(-3.0F, 8.0F);
		private int z1 = Random.Range( 8.0F, 26.0F);
		Instantiate (prefab, new Vector3 (transform.position.x+x1, transform.position.y+y1,Transform.position.z+z1) Quaternion.Euler (270,0,0));


}
}

You forgot a semicolon ; on line 8.

It should be public float myTimer = 15.0;

Try

public Transform prefab;
	public float myTimer = 15.0f;
		
	// Update is called once per frame
	void Update ()
	{
		if (myTimer > 0) {
			myTimer -= Time.deltaTime;
		}
		if (myTimer <= 0) {
			Spawn ();
			myTimer = 15.0f;
		}
	}
		
	void Spawn ()
	{
		float x1 = Random.Range (-6.0F, 13.0F);
		float y1 = Random.Range (-3.0F, 8.0F);
		float z1 = Random.Range (8.0F, 26.0F);	

		Instantiate( prefab, new Vector3(transform.position.x + x1, transform.position.y + y1, transform.position.z + z1) , Quaternion.Euler (270, 0, 0)) ;
			
			
	}