Moving variable value to another php file and send it back

Question

I'm new to php and javascript...So I don't really know how to achieve my goal. Here I have 2 php files, first file :

<?php
    <div class="col-sm-3">
        <label class:>Nama :</label>
    </div>
    <div class="col-sm-9">
        <input type="text" name="nama_tamu" id='nama_tamu' class="form-control" placeholder="Nama Lengkap">
    </div>
    <label>Foto Tamu</label>
    <!-- form yang akan menempatkan jendela webcam untuk menampilkan layar webcam ya....-->
    <p>
        <script language="JavaScript" name="foto" id="foto">
            document.write( webcam.get_html(320, 240) );
            webcam.set_api_url( '../camera/saveImage.php' );
            webcam.set_quality( 90 ); // JPEG quality (1 - 100)
            webcam.set_shutter_sound( true ); // play shutter click sound
            webcam.set_hook( 'onComplete', 'my_completion_handler' );
            <!-- record gambar -->
            function take_snapshot(){
                webcam.freeze();
                var x;
                if (confirm("Simpan gambar?") == true) {
                    x = "Menyimpan gambar ...";
                    webcam.upload()
                } else {
                    x = "Gambar tidak tersimpan.";
                    webcam.reset();
                }
                document.getElementById("upload_results").innerHTML = x;
            }
            function my_completion_handler(msg) {
                // extract URL out of PHP output
                if (msg.match(/(http\:\/\/\S+)/)) {
                    // show JPEG image in page
                    document.getElementById('upload_results').innerHTML ='Penyimpanan berhasil!';
                    // reset camera for another shot
                    webcam.reset();
                } 
                else {
                    alert("PHP Error: " + msg);
                }
            }
        </script>
    </p> 
    <p>
        <input type="button" class="btn btn-warning" value="Ambil Gambar" onclick="take_snapshot()">
        echo $GLOBALS['$imagename'];
    </p>
?>

and the second php file is like this :

<?php
    session_start();
    // untuk membangun koneksi ke database
    include '../config/connect.php';
    $imagename = $GLOBALS['nama_tamu'].date('YmdHis');  
    $newname="../camera/".$name.".jpg";
    $file = file_put_contents( $newname, file_get_contents('php://input') );
    if (!$file) {
        print "ERROR: Gagal menyimpan $filename, cek permissions \n";
        exit();
    }
    else
    {
        // menyimpan gambar ke database
        $sql="Insert into entry(camera) values('$newname')";
        $result=mysqli_query($con,$sql) or die("error sql connect");
        $value=mysqli_insert_id($con);
        $_SESSION["myvalue"]=$value;
    }

    $url = 'http://' . $_SERVER['HTTP_HOST'] . dirname($_SERVER['REQUEST_URI']) . '/' . $newname;
    print "$url\n";
?>

My goal here is I want to send nama_tamu (first php file) value to saveImage.php (second php file) buuut because saveImage.php is called withouth using POST or GET method, so I'm using GLOBALS variable there :

$imagename = $GLOBALS['nama_tamu'].date('YmdHis');

Unfortunaly it doesn't work, and I have no idea how to send this nama_tamu value to saveImage.php... Any idea...???

The second goal is in saveImage.php there is a variable called $imagename. I want to send it's value back to the first php file and print it to the user like this :

echo $GLOBALS['$imagename'];

That doesn't work too...May be because GLOBALS only work for the same file not for different file....!

So any idea how to achieve my two goals here..??? Thanks in advance, I really appreciate your help... :)