How to add CSS code for all posts

CMS & WordPress
1

Hello everyone
My site retete-super.ro with www.
How should I change style.css paste the following code
I want to add CSS code for all posts
Have to change the name. Zit want to change all post but do not know how to add the code.
. zit
{
position: relative;
width: 100px;
height: 80px;
left: 0px;
top: 0px;

 / * Apply the CSS3 Transition to width, height, top and left properties * /
 transition: 0.3s ease width, height 0.3s ease, left 0.3s ease, top 0.3s ease;
 -webkit-transition: 0.3s ease width, height 0.3s ease, left 0.3s ease, top 0.3s ease;
 -o-transition: width 0.3s ease, height 0.3s ease, left 0.3s ease, top 0.3s ease;
 -moz-transition: 0.3s ease width, height 0.3s ease, left 0.3s ease, top 0.3s ease;

}

. zit: hover
{
width: 150px;
height: 120px;
left: 0px;
top:-30px;
z-index: 9999;
}

.'s Zoom
{
clear: both;
}
. Zooming are
{
width: 102px;
height: 82px;
margin: 4px;
float: left;
overflow: visible;
display: block;
}
thank you