When adding a new layer, and needing to coordinate colors how do I do that when the screen is grayed out?

Hello,

Again, I'm really to Storyline so I think I'm going to have a lot of questions so I'll try to use this sparingly...but I am trying to add a button and am adding it as an additional layer. I want the colors of the button to be eyedropped to the color of the background....How am I supposed to be able to do that when the screen is grayed out? 

Also is there a way for colors to be transparent. A shaded red where you can still see the picture parts of the picture in the background?

I really appreciate any help you could provide?

Thanks in advance!