Polymer Dom Insertion Issues

I am using Polymer 1.0, and I'm having a problem retrieving and inserting into the dom and showing. I can get the HTML "li" to print to the console, but I am unable to get polymer to render the HTML.

<example-app appjs="appJsFile.js">
<ul id="content">
//I want Content Here from Polymer
</ul>
</example-app>

appJsFile.js gets imported into "example-app". I have a function for this:

    for(var i in this.listData){
        var _ele = parent.document.createElement('li');
            _ele.innerHTML = this.listData[i].listDataName;
        return _ele;
    }

Any ideas?