I can not centralize the email textbox and password. Here's part of the code and image to help.
<body>
<form id="form1" runat="server">
<!--Começo cabeçalho-->
<header>
<nav class="navbar-inverse navbar-fixed-top">
<div class="navbar-header">
<a href="../Default.aspx" class="navbar-brand">Anqui</a>
<button type="button" data-target=".navbar-collapse" data-toggle="collapse" class="navbar-toggle">Menu</button>
</div>
<div class="collapse navbar-collapse">
<ul class="nav navbar-nav">
<li><a href="About.aspx">About</a></li>
<li><a href="#">Blog</a></li>
<li class="dropdown">
<a href="#" data-toggle="dropdown" class="dropdown-toggle">Entre<span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a href="Login.aspx">Login</a></li>
<li><a href="Cadastro.aspx">Cadastro</a></li>
</ul>
</li>
</ul>
<div class="navbar-form navbar-right">
<div class="form-group">
<input type="text" placeholder="Search" class="form-control"/>
</div>
<input type="submit" value="Buscar" class="btn btn-default"/>
</div>
</div>
</nav>
</header>
<!--Fim cabeçalho-->
<main>
<div class="col-xs-12 col-md-12 text-center">
<div class="text-center">
<h2>Faça login para continuar</h2>
<p>Faça seu login usando seu e-mail e senha</p>
</div>
<div class="col-xs-12 col-md-12 text-center">
<figure>
<img src="../Images/imagem-login.jpg" alt="imagem de login" class="img-circle"/>
</figure>
</div>
<div>
<asp:TextBox ID="txtEmail" runat="server" placeholder="Entre com seu e-mail" width="25%" CssClass="form-control"/></br>
<asp:TextBox ID="txtSenha" runat="server" placeholder="Senha" width="25%" CssClass="form-control" /></br>
</div>
<div class="btn-group">
<asp:Button ID="btnLogin" runat="server" Text="Fazer login" CssClass="btn btn-default" OnClick="btnLogin_Click" />
</div>
</div>
</main>
<footer class="navbar-fixed-bottom">
Anqui © 2016 - Todos os direitos reservados.
</footer>
<asp:ScriptManager ID="ScriptManager1" runat="server">
<Scripts>
<asp:ScriptReference Path="../Scripts/jquery-1.9.0.min.js"/>
<asp:ScriptReference Path="../Scripts/bootstrap.min.js"/>
</Scripts>
</asp:ScriptManager>
</form>
</body>