Click the calendar image on the right side.
<div class="easyui-panel" style="width:100%;max-width:400px;padding:30px 60px;">
<div style="margin-bottom:20px">
<input class="easyui-datebox" label="Start Date:" labelPosition="top" style="width:100%;">
</div>
<div style="margin-bottom:20px">
<input class="easyui-datebox" label="End Date:" labelPosition="top" style="width:100%;">
</div>
</div>