What do I have to do to be able to move to another country with my child?

You mention that you were married ten years ago, but you don't mention whether or not you are divorced or if there are any custody orders in place-- so the answer to your question falls into one of two categories.  The first category is if there are no court orders.  Until there is a court order than gives one parent the main right to establish the residence of the child and another parent visitation rights, then both parents have equal rights.  This means that one parent can relocate with the child, even if the other parent does not approve.  You don't need his permission.  As long as you have a passport for yourself and your child, you can relocate to any place that best helps you take care of your child's needs.  The second category is if there are some type of orders in place.  Orders would include a final decree of divorce or a final judgment on a suit affecting parent child relationship.  If there are orders, you need to get them out and read them and they will tell you what you can and cannot do.  Courts do not frequently restrict where one parent can live.  If your orders do not restrict where you can live, then you can move to Australia without getting permission from the court or your husband.  If your custody papers do contain a geographic restriction, then this does not mean it's set in stone.  You would need to file for a modification of your final order because of a material change in circumstances-- basically that you're a single mom and relocation is essential to providing for your child.  Courts tend to grant these modifications when it's best for the child to be around family and to help the parent with employment, especially in this economy.  If you aren't sure what your custody orders mean, then you may want to have a family law attorney just review them so that they advice can be a bit more specific.  Before you leave, you may also want to consider a couple of things before you leave.  If you are still married-- but no longer want to be married, you may want to get a divorced finalized before he gets out of prison so it will be easier to get him service with notice of the divorce.  If your family is supportive, you may want them to visit with an attorney in Austria to see where you would be better off filing-- here or there.