Save information from a form [closed]

Hello, I'm developing an online proofing system as follows:

Thequestionscomestraightfromthedatabase(MYSQL)andsoIputtheproofshowingquestionbyquestion,whentheusermarkstheanswerandclicks"Next" advances to the next question.

My question is: how do I store in a single variable, be it array or anything, all the answers to the test?

This is the code for my form:

<?php 

require_once('validasessao.php');
$codigo = $_GET['codigo'];

include_once("./classes/conexao.class.php");
include_once("./classes/avaliacoes.class.php");
include_once("./classes/QuestoesDisciplinas.class.php");

$conn               = new Conexao();
$questaoDisciplina  = new QuestoesDisciplinas($codigoDisciplina, $codigoQuestao);
$avaliacao          = new Avaliacoes($codigoAvaliacao, $codigoDisciplina, $dataAvaliacao, $horaInicioAvaliacao, $horaTerminoAvaliacao, $situacaoAvaliacao);

#localizar a avaliação
if($avaliacao->localizarAvaliacao($codigo)){

    #pegar os códigos
    $codigoAvaliacao        = $avaliacao->getCodigoAvaliacao();
    $codigoDisciplina       = $avaliacao->getCodigoDisciplina();

    #buscar as questões
    $res = $questaoDisciplina->buscarQuestoesDisciplina($codigoDisciplina);
    $array = mysql_fetch_assoc($res);   
    if($_POST['numeroQuestao'] == 0) {
        $numeroQuestao = 1;
    } else {
        $numeroQuestao = $_POST['numeroQuestao'];

        $respostaUsuario = $_POST['respostaUsuario'];   

        #$respostas[$numeroQuestao-1] = $respostaUsuario;

        #print_r($respostas);           
    }


    if($numeroQuestao <= $array['quantidadeQuestoesDisciplina']){


<form name = "prova" id = "prova" action = "?pag=provas-p.php&codigo=<?php echo $codigo ?>" method = "POST">
    <table>

        <tr>
            <td><b>Questao <?php echo $numeroQuestao . "/". $array['quantidadeQuestoesDisciplina'] ?></b></td>
        </tr>
        <tr>
            <td><?php echo $array['descricaoQuestao'] ?></td>
        </tr>
        <tr>
            <td>A) <input type = "radio" name = "respostaUsuario" value = "A"><?php echo $array['descricaoResposta1Questao']?></td>
        </tr>
        <tr>
            <td>B) <input type = "radio" name = "respostaUsuario" value = "B"><?php echo $array['descricaoResposta2Questao']?></td>
        </tr>
        <tr>
            <td>C) <input type = "radio" name = "respostaUsuario" value = "C"><?php echo $array['descricaoResposta3Questao']?></td>
        </tr>
        <tr>
            <td>D) <input type = "radio" name = "respostaUsuario" value = "D"><?php echo $array['descricaoResposta4Questao']?></td>
        </tr>
        <tr>
            <td>E) <input type = "radio" name = "respostaUsuario" value = "E"><?php echo $array['descricaoResposta5Questao']?></td>
        </tr>
        <tr>
            <td><br></td>
        </tr>


        $numeroQuestao++;

        <tr>
            <td>
                <input type = "hidden" name = "numeroQuestao" id = "numeroQuestao" value = "<?php echo $numeroQuestao ?>">
                <input type = "submit" name = "enviar" id = "enviar" value = "Próximo">
            </td>
        </tr>
    </table>
</form>

I just want to save the user's response, but I can not do it.