Grass replacement: Open image – place the grass at the top of image layer – mask the grass layer – ctrl+i to invert - click on mask side – brush tool – foreground white background black – brush the image in required areas to fill with grass.
--see video
Dark image make bright: Open image – adjustment layer – brightness – select mask side of layer – ctrl+i to inverse – brush tool – soft brush – flow 22% - foreground/background – white/black – drag on the dark areas to make bright
--see video