transparent moving objects

hi guys! 

I'm new to the community and have a few questions, hopefully someone can help.

I'm building a website and for my header homepage i want to make an animated background overlay with transparant moving parts, so that you can see the image underneath when the moving parts are hovering over the image. For this purpose i need my background to be white and my moving objects (squares, doodles, cirkels, etc.) to be transparent! my question is how?!?! haha is this even possible 

Please help,

Kind Regards Joep 🙂