Atmosphere

Hey, I’m looking for some help and recommendations. Currently I have created a scene where a stick figure walkes along a park street and then sits on a bench and this is all taken place at night , now all the modeling is done but I am wanting to make the atmosphere in the scene kind of misty/foggy but I’m not sure where to start going about with atmosphere in my scene and looking for anyone to point me in the right direction possibly with what tutorials I should watch or just anything that will help me create the scene I’m after ,Thanks in advance