No worries. It’s good to have a stab at something every now and then in Blender. Eventually, you’ll find you can start to make rudimentary assets, and it will grow from there.
Get a copy of Blender from blender.org.
When you start, you’ll have a cube in the scene. Delete that.
Top left menu, Add → Mesh → UV_sphere. You get a raggedy sphere. Don’t click on anything else and you’ll notice bottom left, there’s a collapsed menu, also called ‘UV Sphere’.
Open that, and you can change the number of segments and rings to something like 128x128. Don’t scale it up here, unless you want a bit more of a crash course.
Now right click on there sphere and choose ‘shade smooth’.
Then in the main menus File → export → FBX: On the right click ‘selected objects’ ( otherwise you get the camera and light ).
Now in UE content browser: right click on the background and choose ‘Import to /Game/…’ and choose your file.
UE will whine about smoothing groups, but that’s basically it 