TOTAL beginner - how do I change the default header image?

Hi, I am a TOTAL beginner to coding, WordPress, and any sort of web-building whatsoever. So sorry to ask an obvious question, but how do I insert a JPG image I have on my computer to be the header image in this theme???? So far, I have:
1. uploaded the .jpg to my "Media Library" on Word Press
2. gone to the "Edit Themes" page/stylesheet "Header (header.php)"
3. figured out that deleting or changing this code is the key to changing the header image:

<tr>
<!-- Header -->
<td id="header" colspan="<?php echo $bfa_ata['cols']; ?>">
<?php bfa_header_config($bfa_ata['configure_header']); ?>
</td>
<!-- / Header -->

<!-- Header -->
<td id="header" colspan="<?php echo $bfa_ata['cols']; ?>">
<?php bfa_header_config($bfa_ata['configure_header']); ?>

</td>
<!-- / Header -->
</tr>

After that I'm totally stuck!!! Can someone please help with simple instructions on what to type in this section?

thank you thank you.