Sons autism

Hello everyone I'm Laura.  My 5 year old child has sensory disorder and has just been diagnosed with autism. Im just wondering where do I go from here? I feel at a loss tbh.  He Is doing well at school but at home it's like he is a totally different person. He hits out at me alot and at his older brother who is 15 they dont get on at all which is very upsetting for me. I want to be able to help son as much as possible so any advice is welcomed. Thank you