please, can somebody help me?

I ll create black layer in blue voda which will be fixed at the top or at the bottom of the webpage. If you ll scroll the self webpage you can always see this black layer at the top or bottom. This layer I will have on the full width of the webpage in case if the visitor will change the size of the page.
I tried the sticky layer in blue voda, this is ok, but it dont suit me if the layer make the movement after the scrolling of the webpage.
Can also somebody help me, what I should set in Layer Properties in BV?

All help is highly appreciated
Thank you
Kind regards