Here is a list of websites, fidgets/toys, and books that I enjoy and consider resourceful. There are many different ways to find help online.
Asking autistic adults is a great way to talk to others who might be or might have been in your situation, or are better apt to understand how to help autistic children. Common places to find like-minded people would be Facebook groups and Twitter tags (#ActuallyAutistic, #AllAutistics, #AskingAutistics, #OpenlyAutistic, etc.)
Here are other resources I’ve found helpful:
Thinking in Pictures by Temple Grandin
NeuroTribes by Steve Silberman
Asperger’s Couple’s Workbook by Maxine Aston
Autism Research Institute: 866-366-3361
American Autism Association: 877-654-GIVE