I have a minimap on the top right of my screen, and would like to add a border/background under it that way I can see it more clearly! Is there anyway to add an image under the minimap?

I have a minimap on the top right of my screen, and would like to add a border/background under it that way I can see it more clearly! Is there anyway to add an image under the minimap?

I have an image that I want to be invisible at the start of the game and then pop up later on screen to be hidden again later.
This is the code I have for making the image in the create function: