Setting a cookie pop-up

I'm trying to do the typical pop-up that every page has now. "This site uses cookies. By continuing to browse the site, you are agreeing to our use of cookies."

I have created this code to make the pop-up dissapear by clicking the close button, but everytime I load the page, the pop-up is still visible...

I would also like to know what's the normal cookie's time expiration for these kind of pop-ups...

Can you help me?

HTML5

<div id="cookies_alert">
  <div class="cookies_container">
    <div class="cookies_close"></div>
       <div class="cookies_text">This site uses cookies. By continuing to browse the site, you are agreeing to our use of cookies.</div>
  </div>    
</div>

CSS3

    #cookies_alert {
    bottom: 20px;
    height: auto;
    left: 0;
    margin: 0 auto;
    padding: 0;
    position: fixed;
    right: 0;
    width: 320px;
    z-index: 998;

    -webkit-transition: all 0.5s ease-out;
       -moz-transition: all 0.5s ease-out;
         -o-transition: all 0.5s ease-out;
            transition: all 0.5s ease-out;
}

#cookies_alert.closed {
    bottom: -120px;

    -webkit-transition: all 0.5s ease-out;
       -moz-transition: all 0.5s ease-out;
         -o-transition: all 0.5s ease-out;
            transition: all 0.5s ease-out;
}

#cookies_alert .cookies_container {
    background-color: rgba(0,0,0,0.85);
    padding: 15px;
    padding-right: 35px;
    position: relative;
}

#cookies_alert .cookies_close {
    background-image: url("../images/menu.svg");    
    background-position: center -13px;
    background-size: 13px;
    height: 13px;
    position: absolute;
    right: 10px;
    top: 10px;
    width: 13px;
}

#cookies_alert .cookies_close:hover { cursor: pointer; }

#cookies_alert .cookies_text {
    color: #FFF;
    font-family: Comfortaa;
    font-size: 0.8em;
}

#cookies_alert .cookies_text a { color: #EA504E; }

#cookies_alert .cookies_text a:hover { text-decoration: underline; }

JS

$('.cookies_close').on('click', function () {
    if($.cookie('Terms')){
        $('#cookies_alert').addClass("closed");
    } else {
        $.cookie('Terms', 'Terms', { expires: 7 });
        $('#cookies_alert').removeClass("closed");
    }
});

P.D.: I'm using a JQuery Cookies Plugin... http://ift.tt/1zsvKxm