title: How to install my own firefox extension
body: <p>I am new to FF extensions development. I work on Windows OS. I am using web extensions. I started my first extension. I created a directory in <code>My Documents</code> which contains my extension files. The files are based on the example in: <a href="https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Your_first_WebExtension" rel="noreferrer">Your First WebExtension</a> which are: <code>manifest.json</code>, <code>icons/myicon.png</code>, <code>myextension.js</code>. Like the example, all what the extension does is a border aroud mozilla page. This is the js code: <code>document.body.style.border = "5px solid red";</code> </p>
  
  <p>When I come to installing the extension in my browser, I navigated to:<code>about:debugging</code> then I clicked in the <code>Load Temprary Addon</code> button and I selected the the <code>.js</code> file. I get this error: <code>There was an error during installation: Extension is invalid</code>. Can you point what the problem is? </p>