Welcome to CiC. Could you please go to your profile at the top right and add your name and location? We use real names here.
A good place to start with many questions is with the tutorials on this site. There is one that discusses banding noise:
https://www.cambridgeincolour.com/tu...mage-noise.htm
the most efficient thing is to start with the tutorial and then post questions about anything that is still not clear. That's more efficient and will get you clearer answers than having us all start ad hoc.
Dan