UPDATE DEC 25th 2022:
The PSD template has been revised slightly due to changes made on FA that just barely misalign the icon with the banner. Redownload the template using the same link below and it should be updated. The preview in this submission is not updated because I'm lazy but the changes are pretty subtle anyway.

Download PS Template for FurAffinity Banners here: https://levi.land/FABanner

Use this template to create seamless banners on FurAffinity where both the icon and banner are part of one large picture!

You can also use this to preview what your banner will look like on the site.

NOTE: This will not work on mobile, there's no way to make a banner which will work seamlessly on both mobile and desktop, so I chose to make this template for desktop.

INSTRUCTIONS

Open the file in Photoshop.

Double-click the thumbnail for the layer marked "PLACE ARTWORK HERE". This will open a new Photoshop document.

Open your desired artwork in Photoshop, and drag it into the document we opened by double-clicking that layer thumbnail.

Transform and align the artwork so that it lines up the way you want it. The guidemarks in the document shows you where the icon needs to be framed. Make sure the artwork layer is placed between the two red layers.

Anything that is highlighted in red won't be visible on the banner.

Once you're happy, press CTRL+S (CMD+S on Mac) to save the document and then close the tab. Now you should see your edit reflected in the main document.

To save the images you'll need, go to File > Export > Export As...

Uncheck the artboard called "FA Preview" unless you want to keep it for some reason. Change the format to JPG, maximum quality, leave everything else alone and click "Export". Select a file destination and you're done! Enjoy!