Como subir archivos en php?

[vashzero]

Muy buenas tardes.

Que pena, me gustaría saber como hago para subir archivos en php? He encontrado MILES de soluciones en la web, pero ninguno me sirve, este me arroja este error, alguien sabe que podría ser?

Warning: move_uploaded_file(/home/web/public_html/prueba/prueba/upload/chile.jpg) [function.move-uploaded-file]: failed to open stream: No such file or directory in /home/web/public_html/prueba/prueba/agregar_.php on line 115

Warning: move_uploaded_file() [function.move-uploaded-file]: Unable to move '/tmp/phpuib0Rh' to '/home/web/public_html/prueba/prueba/upload/chile.jpg' in /home/web/public_html/prueba/prueba/agregar_.php on line 115
Error: A problem occurred during file upload!

Y el código es este:

En el formulario agregar.php (ES UNA PARTE). LO NEGRIADO ES DONDE ESTÁ LA PARTE DE UPLOAD.

<tr>
<td><div align="right"><strong>Año&nbsp;&nbsp;</strong></div></td>
<td><label>
<input type="text" name="año" size="30" id="año" />
</label></td>
</tr>
<tr>
<td><div align="right"><strong>Pdf&nbsp;&nbsp;</strong></div></td>
<td><label>
<input type="text" name="pdf" size="30" id="pdf" />
</label></td>
</tr>
<tr>
<td><div align="right"><strong>Software&nbsp;&nbsp;</strong></div></td>
<td><label>
<select name="software" style="width:15.7em">
<option name="SI" value="SI">SI</option>
<option name="NO" value="NO">NO</option>
</select>
</label></td>
</tr>
<tr>
<td><div align="right"><strong>Subir Software&nbsp;&nbsp;</strong></div></td>
<td><label>
<input type="hidden" name="MAX_FILE_SIZE" value="100000000" />
<input name="uploaded_file" type="file">
</label></td>
</tr>

agregar_.php

if((!empty($_FILES["uploaded_file"])) && ($_FILES['uploaded_file']['error'] == 0)) {
//Check if the file is JPEG image and it's size is less than 350Kb
$filename = basename($_FILES['uploaded_file']['name']);
$ext = substr($filename, strrpos($filename, '.') + 1);
if (($ext == "jpg") && ($_FILES["uploaded_file"]["type"] == "image/jpeg") &&
($_FILES["uploaded_file"]["size"] < 350000)) {
//Determine the path to which we want to save this file
$newname = dirname(__FILE__).'/upload/'.$filename;
//Check if the file with the same name is already exists on the server
if (!file_exists($newname)) {
//Attempt to move the uploaded file to it's new place
if ((move_uploaded_file($_FILES['uploaded_file']['tmp_name'],$newname))) {
echo "It's done! The file has been saved as: ".$newname;
} else {
echo "Error: A problem occurred during file upload!";
}
} else {
echo "Error: File ".$_FILES["uploaded_file"]["name"]." already exists";
}
} else {
echo "Error: Only .jpg images under 350Kb are accepted for upload";
}
} else {
echo "Error: No file uploaded";
}

Agradezco si alguien me puede ayudar URGENTE!!! con este problema.

Un saludo y excelente página..