Using alphas in FCPX

I have a PNG logo that is black on a transparent background. I want to use this logo in FCPX for an edit, but I want to invert those selections (i.e. I want the logo to be transparent and for the space around it to be black) so that when I lay the logo over some footage in my timeline, I can see the footage through the logo.

I've been watching some YouTube tutorials, and playing around with Keyer / Luma Keyer for a while, but haven't been able to figure it out just yet. But I'm pretty sure I'm staring straight at the solution, I just need a sharper mind to help point me in the right direction!

Thanks for your help folks.

(Running FCPX 10.5.4)