I want to change my boot screen wallpaper

[ItalianFX]

I don't even know what it is called so I don't even know what I need to search for. I found one thing, but it wasn't what I wanted.

I used to trade foreign exchange with Tradestation and when I downloaded their program, they placed their logo as a screen right before my computer boots up. I always have to put in a password to login to windows, so the screen with the TS logo would be right before the password screen comes on. I'm sure most of you know what I am talking about.

It has been like 3 years now and I want to change it either to what it used to be (?) or to something else.

Does anybody know what it is called or know how to change it?

Thanks!