The first thing you’ll need is a Heraldic Scroll, that allows you to write your heraldry on a scroll.
After you customized your heraldry to the best of your design skill (note, you must press the “Done” button!), it’s time to put it in the world. You can either hang it in a wall or put it on the floor, pick your poison, wall and floor, respectively:
OK, now you have an empty banner and a scroll, what now? Well, easy, just plonk the banner down on the ground like a regular block (note, it needs 2 block high clearance, for both wall and floor banners) and right click it with your scroll (it won’t get consumed). And bob’s your uncle, you got your banner.
There are 876 different icons you can pick for your heraldry. All of them gotten from the amazing Lorc, at game-icons.net!