@Debbie: That button uses the following css:
#homepage-message .right-section a {
    background-color: #28b3c5;
    border: 2px solid #fff;
    border-radius: 5px;
    -moz-border-radius: 5px;
    -webkit-border-radius: 5px;
    box-shadow: 0 -3px 0 rgba(0, 0, 0, 0.2) inset;
    color: #fff;
    display: block;
    padding: 10px 25px;
}
#homepage-message .right-section a:hover {
    background-color: #28b3c5;
    box-shadow: 0 3px 0 rgba(0, 0, 0, 0.2) inset;
    text-decoration: none;
}
So, if you want to create link with class then you can add link as
<div class="pro-button"><a href="yourlink.com">Your text</a></div>
Then you can add css like below:
.pro-button a {
    background-color: #28b3c5;
    border: 2px solid #fff;
    border-radius: 5px;
    -moz-border-radius: 5px;
    -webkit-border-radius: 5px;
    box-shadow: 0 -3px 0 rgba(0, 0, 0, 0.2) inset;
    color: #fff;
    display: block;
    padding: 10px 25px;
}
.pro-button a:hover {
    background-color: #28b3c5;
    box-shadow: 0 3px 0 rgba(0, 0, 0, 0.2) inset;
    text-decoration: none;
}