Firstly, welcome to the world of ASD. I'm sorry you haven't had much luck re information and knowing where to seek help.
How old is your son that was just diagnosed and which state are you from? I too am new to this journey. Our son was only diagnosed in August at 20mnths and is now 2
We have the best Paed who gave us all the information we needed to get started.
Do you see a paediatrician for your son? I'm no expert but here is some info from our journey thus far that might be of assistance.
Ok so if you do have a Paed you see regularly or even a Family GP they will be able to recommend some good Therapists in your area. They can be costly however some do accept the medicare plan/medicare rebate I would ask your GP about this to get more precise info. Now that you have your diagnosis (keep the diagnosis statement safe) you will be able to apply for the FAHCSIA Funding or Helping Children with Autism Funding which is off the top of my head $12k until your child turns 6 or the day before their 7th birthday but you cannot use more than $6k in one financial year. You can simply download an application form through AMAZE or contact them for help and they will arm you with everything you need to know including eligibility and process. You should also now be eligible for the Carer's allowance through Centrelink. If you still see a maternal health nurse or through your GP/Paed you can enquire about Early Childhood Intervention Services (ECIS) the wait times are long roughly 6-12mths and is funded by the Dept of Education. We are still on the wait list for this service (approx. 7mths now) but an application has to be put fwd to them through your MHCN, Paed or GP.
There are various playgroups you can join for your son but My Time group sessions are aimed at Parents and is a great opportunity to meet other parents on the same journey as you and also a chance to get some beneficial information.
You can also learn A LOT just using google
there are numerous blogs and online information you can browse through. Especially if you have a few questions and want/need them answered immediately.
I hope this information makes sense and at least gives you a little bit of guidance. I'm not on facebook so I'm not sure about the private group sorry hopefully someone else can assist you with that.
I wish you and your family all the best on this new adventure. It is no doubt a roller coaster ride at times but very rewarding too.