I do not know what you will actually do but this is the approach that best fits
when you put a file type in your form, you need to use the global variable Files
form.html
<form action="process.php" method="post" enctype="multipart/form-data">
<label for="picture">Picture:</label>
<input type="file" name="picture" id="picture"><br>
<input type="submit" name="submit" value="Upload">
</form>
process.php
<?php
session_start();
//make sure you have created the **upload** directory
$filename = $_FILES["picture"]["tmp_name"];
$destination = "upload/" . $_FILES["picture"]["name"];
move_uploaded_file($filename, $destination); //save uploaded picture in your directory
$_SESSION['user_name6'] = $destination;
header('Location: display_picture.php');
display_picture.php
<?php
session_start();
?>
<div>
<img src="<?php echo $_SESSION['user_name6']; ?>" alt="picture"/>
</div>