Welcome to the forum!
I'm not clear why Lazur suggests that. Wouldn't you end up with just what's already there?
Oh hey, it's an animation! If you click on the attachment, you'll see it's like a video (except is an animated GIF)! (I'm not sure if it has to be embedded in the message, to play like a video, maybe?)
Unfortunately, I can't tell what's happening. If I watch the mouse, I miss the key. If I watch the key window, I miss what the mouse is doing. I see you had the Tweak tool for a minute, but for the rest, I was lost.
I do have the impression cmbdii wants to put a different color in each space, though.
There are a couple of ways to approach this, and I guess it depends on your goals, which way you go. I would probably use Paint Bucket tool myself.
But when you say it goes gray -- what goes gray? If you mean the space that you want to fill goes gray, that's fine. Now just change it to the color you want. If you mean the green part goes gray, then you probably didn't click over the empty space. If it's something else, please explain more.
Tips for the Paint Bucket tool:
-- Zoom so that the space you want to fill, almost fills the window. If the space you want to fill is larger than the window, it might not all be filled. And if the space is too small, it's hard to click in the open space.
-- Use the Grow/Shrink setting on the contol bar. This tool works best when the space you want to fill is zoomed to fit the window. But it still leaves a little gap between the fill path and the edge of the space. If the space is smaller than the window, that gap is larger. In any case, you can use Grow/Shrink to help fill the gap.
I say "help" fill the gap, because if you need the fill path and the edge of the space to meet precisely, you'll need to do a lot of manual tweaking of nodes and node handles. But if having some underlap is ok, then I usually set the Grow to about 5. That will make sure that the whole space is filled. Then I simply move it behind the large object. As long as the larger object doesn't have any transparency, or you aren't going to use a filter on it, that works very well.
At the end, select everything and group it together. That will make it move all at once, and you won't accidentally lose parts