<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<form class="form-horizontal">
<fieldset>
<div class="row">
<div class="col-md-6">
<div class="form-group">
<label class="col-md-4 control-label" for="PRNumber">PR #</label>
<div class="col-md-4">
<input id="PRNumber" name="PRNumber" type="text" placeholder="PR #" class="form-control input-md">
</div>
</div>
<div class="form-group">
<label class="col-md-4 control-label" for="VendorInvoiceNumber">Vendor Invoice #</label>
<div class="col-md-4">
<input id="VendorInvoiceNumber" name="VendorInvoiceNumber" type="text" placeholder="placeholder" class="form-control input-md">
</div>
</div>
<div class="form-group">
<label class="col-md-4 control-label" for="ddlVendorCode">Vendor/Code</label>
<div class="col-md-4">
<select id="ddlVendorCode" name="ddlVendorCode" class="form-control">
<option value="1">Option one</option>
<option value="2">Option two</option>
</select>
</div>