Hello,
It is my second and third work in Blender.
I must practice with light because I have feeling that everythink on the scene is merging and shadow is too weak
Noise is because Blender calculations doesn’t fill in those noise spots.
And that is because your sample rate is to low, for the amount of light bouncing around the scene.
You can go higher in the samples rate (longer render times).
Or increase light in the scene by adding more lamps. Or increase the light emission intensity.
But a cheap way is to use the de-noise option. With Blender 2.8 de-noising is very good in blender, but it has it’s own problems (image can get fuzzy). It all depends on what you what to show in your scene.
Easiest way is to stick at Eevee, with fast render times. It will help you finish quickly some challenges in this course.
Oh thanks a lot! 
denoise option helps.
I wanted to stick at Cycles because of better shadows. On Eevee I couldn’t do shadows as good as on Cycles.
