How to Sync List

Hello, i need to sync vector3 list that i stored so clients can see positions of the LineRenderer that i used for painting
I’m kinda trying to make multiplayer painting game

I can’t just type [SyncVar] on top of it.

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using UnityEngine.Networking;

public class StoreLineRenderValues : NetworkBehaviour {
	public List<Vector3> positions;


I searched a lot and i found struct but i have no idea how to use it


Well i converted it to array and stored it inside Vector3 then i used [ClientRPC] and [Command] to send the arrays