Dark Top Bbs How Do I Fade My Room From Dark At The Top To Light At The Bottom?

How do I fade my room from dark at the top to light at the bottom? - dark top bbs

I paint my room and I wanted to look washed. I want to know how to make a look melted, mix up gradually in the dark blue on the floor. Any tips? I'm not sure how to do if someone could tell me how or show me a website, it would be great! Thank you!