<?php

include './DAOAdministracion/DAOCategorias.php';
include './conexion.php';
$cn = new coneccion();
$cn->Conectarse();
$daoCategoria = new DAOCategorias();
$rs = $daoCategoria->guardarCategoria($_GET["categoria"]);
if ($rs == false) {
    echo mysql_error();
} else {
    echo 'Nueva Categoria Disponible';
}
<?php

include './conexion.php';
include './DAOAdministracion/DAOCategorias.php';
$cn = new conexion();
$dao = new DAOCategorias();
$cn->conectarse();
$rs = $dao->dameCategorias();
?>
<section>
    <div class="w-section inverse">
        <div class="row" style="height: 200px">
            <div class="col-md-6 col-md-offset-3 col-sm-6 col-sm-offset-3">
                <div class="w-section inverse">                       
                    <div class="w-box sign-in-wr bg-5">
                        <div class="form-header">
                            <h2>Modulo de categorias</h2>
                        </div>
                        <div class="form-body">
                            <form role="form" class="form-light padding-15">
                                <div class="form-group">
                                    <label>Categoria.</label>
                                    <input type="text" class="form-control" id="txtCategoria" 
                                           placeholder="Categoria....">
                                </div>
                            </form>
                            <input type="submit" 
                                   onclick="guardarCategoria();"
                                   class="btn btn-primary"
                                   value="Guardar Categoria"/>
                        </div>