Revamping my Journal

I want to revamp my journal but I haven't the faintest idea how to go about it :( Does anyone know how you add a banner to the top?? I'd like to do a Merlin themed one of some kind. I have this banner saved from ages ago (if anyone can remember who did it, please let me know! Normally I try and save the author in the file name but this time I haven't for some reason) and I would love to use it.



I'm just a bit bored with the layout as it is, as lovely as the cavorting historical dudes are of course.

Suggestions/tips welcome!

ETA: I CANNOT BELIEVE HOW COMPLICATED THIS IS. Looks like Cavorting Historical Dudes and I will be together for some time.