Discover how to create stunning photo manipulations in Photoshop. In this course, you'll learn everything from photographing models to creating dark conceptual artworks. If you enjoy our photo manipulation tutorials, you will absolutely love this course.
Add a Layer mask to each star layer (Layer > Layer Mask > Reveal All or use icon on Layer panel). Use Brush Tool (B) with created brush (Size: 400px, Opacity: 70-40%) to remove excess stars texture. Try not to repeat the previous layer mask and put stars in the same place. Make texture varied and where you plan to place Nebula (or the main object). It is important to make the texture varied that there were clusters of stars, and some parts.
Now I have created a nebula. It's very simple, create new layer (Cmd/Ctrl + Shift + N). Use Elliptical Marquee Tool (M) and draw an ellipse almost the entire width of the worked area. In principle, not necessarily to use this tool. You need to create an area desired shape. Right click on the circle and select "Feather", enter of feather radius 45px and click Ok. This is to soften the edges of the future nebula.