What can I say. You are looking for help with light but you still have to work on base sketch and perspective.
Tiles on left wall look bit off and disturbed. I can imagine you didnt want all tiles to be same size but that just look weird. Try to draw some grid with line tool and than skew it to see if perspective goes well.
About characters: there are some anatomic issues. Lets take a girl- her right arm seams to be longer than left one also her left hand is bit small.
Legs of that standing dude are twisted. Try to stand like him and you will see its almost imposible. His left leg looks broken and distorted outwards at the knee. Same refers to his right foot.
Fallen guy also needs some work on his pose. Get some references, they might help you.