Upload a header to a website

I am working on a adult dating website project, in order to complete it I need to create a back end for it through

I have completed most of it but I just need to upload a header through the portal. I have already created this header in the correct format, it just needs to be uploaded using image tags.

I have attached a screenshot of the actual page where it is required, I just don't have the technical knowledge to do so.

Please feel free to ask any questions!

Thanks for reading!