<link href="//netdna.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<form class="form-horizontal">
<fieldset>
<legend>Form Name</legend>
<div class="control-group">
<label class="control-label" for="Nome">Nome</label>
<div class="controls">
<input id="Nome" name="Nome" placeholder="Nome Completo" class="input-large" type="text">
</div>
</div>
<div class="control-group">
<label class="control-label" for="email">E-mail</label>
<div class="controls">
<input id="email" name="email" placeholder="Digite seu e-mail" class="input-large" type="text">
</div>
</div>
<div class="control-group">
<label class="control-label" for="assunto">Assunto</label>
<div class="controls">
<input id="assunto" name="assunto" placeholder="Digite o assunto da mensagem" class="input-large" required="" type="text">
</div>
</div>