You can add graphic elements like that in to the game by using one of a few mods out there.
Something like Discord art will certainly allow you to add elements like that as will Eepanels. I know there are other mods for it as well the names just escape me currently.
Eepanels2 can be found at wowace.com and Discord art and related discord mods can be found at
http://underworldexodus.com/forum/forum.php.
The graphic files need to be in powers of 2 so 64, 128, 256, 512 i forget if there are min/max sizes ( i personally just stay between those numbers) and require an alpha channel. .tga format works nicely though i believe there are others.
that should cover the basics. There should be a sticky with more detailed info in this forum.
Enjoy=)