Amazing !! 
May I ask which tutorial did you follow ?
In any case, keep going ! 
Thank you! Here’s the tutorial:
by Wayward Art Company
The landscape looks really great, but I LOVE that sky and am wondering how you did it. Is it an HDRI, sky addon, or a combination of volumetric clouds and either a sky texture (like nishita) or gradient?
Thanks for commenting. The sky is simply an image plane set to emission and in render settings, shadow disabled. The subtle shadow over the landscape is created by a hug plane with a noise texture plugged into the alpha. It is blocking the light from a nishita sky texture. I manually positioned the nishita sky to closely resemble the shadows in the clouds from the background image.
You integrated it into the scene flawlessly.
I featured you on BlenderNation, have a great weekend!
Wow! Thank you for this 
Great encouragement in these troublesome times!