Does anybody know anything about workers compensation??I need help learning more about this?

My boyfriendis a cna and got into an accident almost a year ago at his job with a patient. The patient was fighting with him and he ended up tearing his acl? i think thats what its called. its something in the knee and never heals back to normal. but its been so bad these last few months he sometimes cant walk and he cant get the jobs he needs to get to support us and our unborn baby. He could get surgery to make his knee much better then it is now but we literally have no money. Can anybody tell me how workers compensation works? What exactly do i need to do to get it? Who exactly do i need to call what do i need to ask? And how much is it going to cost to get somone to help us? Do we need a lawyer or someone if so how much will that cost? Any websites to help me learn more?