how to make a form that uploads files via php

<form action="upload_file.php" method="post"<br />enctype="multipart/form-data"><br /><label for="file">Filename:</label><br /><input type="file" name="file" id="file" /> <br /><br /><br /><input type="submit" name="submit" value="Submit" /><br /></form><br />
and then on your processing page

<br /><?php<br />if ((($_FILES["file"]["type"] == "image/gif")<br />|| ($_FILES["file"]["type"] == "image/jpeg")<br />|| ($_FILES["file"]["type"] == "image/pjpeg"))<br />&& ($_FILES["file"]["size"] < 20000))<br /> {<br /> if ($_FILES["file"]["error"] > 0)<br /> {<br /> echo "Return Code: " . $_FILES["file"]["error"] . "<br />";<br /> }<br /> else<br /> {<br /> echo "Upload: " . $_FILES["file"]["name"] . "<br />";<br /> echo "Type: " . $_FILES["file"]["type"] . "<br />";<br /> echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";<br /> echo "Temp file: " . $_FILES["file"]["tmp_name"] . "<br />";<br /><br /> if (file_exists("upload/" . $_FILES["file"]["name"]))<br /> {<br /> echo $_FILES["file"]["name"] . " already exists. ";<br /> }<br /> else<br /> {<br /> move_uploaded_file($_FILES["file"]["tmp_name"],<br /> "upload/" . $_FILES["file"]["name"]);<br /> echo "Stored in: " . "upload/" . $_FILES["file"]["name"];<br /> }<br /> }<br /> }<br />else<br /> {<br /> echo "Invalid file";<br /> }<br />?><br />