<form action="request.php" method="POST" id="frmLogin">
    <input type="text" id="edtLogin" />
    <br />
    <input type="password" id="edtPassword" />
    <br />
    <input type="submit" value="Login" id="btnLogin" />
</form>
<script type="text/javascript">
    $(document).ready(function()
    {
        $("#frmLogin").submit(function(e)
        {
            // Sitais ir lai nesubmitojas forma, kad nospiez us pogas
            e.preventDefault();

            // Sutam POST
            $.post("request.php",
                {
                    login       : $("edtLogin").val(),
                    password    : $("edtPassword").val()
                },
                function(postBack)
                {
                    // postBack = Hello from request.php!
                    alert(postBack);
                }
                .error(function()
                {
                    // Kaut kas nesanaca
                    alert("Error...");
                })
            );
        });
    });
</script>