How to make a plugin with file upload

Hi, i’m trying to write a plugin and I need the admin to have the option to upload files(images). As of the moment i got:

<form method="post" action="options.php" enctype="multipart/form-data">
    <?php wp_nonce_field('update-options'); ?>
    <table width="100%" style="text-align: left;">
        <tr valign="top">
            <th width="250" scope="row">Background Image</th>
            <td>
                <input name="mypg_image" type="file" id="mypg_image" value="" />
            </td>
        </tr>
        <tr valign="top">
            <th width="250" scope="row">Image Title</th>
            <td>
                <input name="mypg_title" type="text" id="mypg_title" value="<?php echo get_option('mypg_title'); ?>" />
            </td>
        </tr>
    </table>

    <input type="hidden" name="action" value="update" />
    <input type="hidden" name="page_options" value="mypg_title, mypg_image" />
    <p>
        <input type="submit" value="<?php _e('Save Changes') ?>" />
    </p>
</form>

and there is no problem working with the text fields, but how should a file upload be managed ?