PLEASE HELP! 4 year-old broken leg!!!?

Hello, I'm new here, my 4 year-old son broke his leg, none of us have broken anything and don't know how much pain or what else is our son feeling like, what to do with him? keep him in bed all time? he broke his lower leg is casted from his thigh to his toes, they are swollen right now, please answer this question, we need lots of help, please help, we are very new to this, we are very thankful with all the answerers. THANKS