Error adding extension to google chrome

So I'm getting started in on making chrome extensions and I find it confusing to understand JSON because I don't have too much experience with it. I'm trying to connect my JavaScript to the extension but it says it's not secure. Can somebody tell me whats wrong with my code?



  <link rel="stylesheet" href="style.css">
  <script type="text/javascript" src="script.js"></script>
  <title>Miguel Betancourt</title>

  <div class="extenContainer">
    <h3 class="logo"></h3>

  <div class="counter">
    <button onclick="plus()">test</button>
    <a href="#"<div class="buttonL" onclick="minus()"></div></a>
        <p id="number">0</p>
    <a href=""<div class="buttonR" onclick="plus()"></div></a>




var add = (function () {
    var counter = 0;
    return function () {return counter += 1;}

function myFunction(){
    document.getElementById("demo").innerHTML = add();


  "manifest_version": 2,

  "name": "Poop Counter",
  "description": "How much have you pooped?",
  "version": "1.0",

  "browser_action": {
    "default_popup": "popup.html"


  "permissions": [

      "matches": ["*"],
      "css": ["style.css"],
      "js":  ["script.js"],