PLS HELP! How to fire a remote event when a Humanoid is found inside of a Region3?

Also how would I change the blur on the screen that you can put into lighting for the client? I'm doing a remake of a Camping and I'm trying to check if a Humanoid is inside of a Region3 and then make their screen blurry with the Blur effect inside of lighting. If you need a script from my game just ask :D