Edit in JSFiddle

$(function () {
    $("#foo").before("<div class='before'>before</div>");
    $("#foo").after("<div class='after'>after</div>");
    $("<div class='before'>insertBefore</div>").insertBefore("#bar");
    $("<div class='after'>insertAfter</div>").insertAfter("#bar");
});

<div id="foo" class="container">foo</div>
<br />
<div id="bar" class="container">bar</div>

div.container {
    background-color:yellow;
}
div.before {
    border: solid 1px blue;
}
div.after {
    border: solid 1px red;
}