//insert new Element after some reference Element
function insertAfter(newElement, referenceElement) {
    referenceElement.parentNode.insertBefore(newElement, referenceElement.nextSibling);
}

//example usage
var newElement = document.createElement("div");
    newElement.innerHTML = "my New Div Text";
var myCurrentElement= document.getElementById("myElementID");
    insertAfter(newElement, myCurrentElement);