No problem. Go to the Media section of your WordPress control panel and select Add New. Upload the image. Once the upload completes, click the edit link. After that screen loads, look on the right and you’ll see a field for the file URL. Copy that URL.
Now go back and edit the footer.php file again. In the snippet I gave you above, replace this:
http://www.flamesofrevival.co.uk/wp-content/uploads/upfw/newfofrlogotranparentfinal.png
with the URL you copied just a moment ago. Then save your changes.
That will use the new logo in the footer.
Let me know if you have any questions or trouble,
Bill