title: Disable Button till password/access code entered (PHP)
body: <p><strong>Edit: Apologies for the bad wording, a better version is below:</strong>
  When the user first visits the site they see i.stack.imgur.com/7zbyv.png. They then have to enter a set password (PHP variable) and click submit. If it is correct i.stack.imgur.com/E78wK.png will show. If not, nothing will happen.</p>
  
  <hr>
  
  <p>I am working on a script over at my development site. I am looking to replace the big green button with a text box and a submit button. The user must enter the correct password into the box and click the submit button before the green button is displayed. I cannot find a guide on how to do this anywhere. Can anyone help me? I have put the relevant code and screenshots below:</p>
  
  <p>Green Button:</p>
  
  <p><img src="https://i.stack.imgur.com/E78wK.png" alt=""></p>
  
  <pre><code>&lt;?php
      if(($xx != null) || $log != null)
      {
      echo "&lt;a rel=\"tooltip\" title=\"Login via Instagram using your username\" class=\"btn btn-success\" href=\"$loginUrl\"&gt;Login with Instagram&lt;/a&gt;";
      } 
  ?&gt;
  </code></pre>
  
  <p>Login Form and Button</p>
  
  <p><img src="https://i.stack.imgur.com/7zbyv.png" alt=""></p>
  
  <pre><code>&lt;form&gt;
          &lt;br /&gt;
          &lt;input type="password" class="input-small" placeholder="Enter Code..."&gt;
          &lt;button type="submit" class="btn"&gt;Login&lt;/button&gt;
  &lt;/form&gt;
  </code></pre>