prodsix

I'm new to paint.net I was wondering what is the best way to blend new space in a photo to make it perfect in the photo below it's an album cover and I'm trying to use it for something, but want it to be a 1920x1080 photo, I'm not sure what the best way to make the whole sky fill up the black bars too so that it blends perfectly, I tried using some tools but you can see where the colors clash where it's lighter and darker, big rookie here, have no idea how to do this I