In Azure, when you create VNET, you create Address space. In your case, the address space is 192.168.0.0/16. Once that is created, you need to create subnets on which you will be able to deploy any resources.
Address space is the super set and the subnets are the subsets of Address space. If you want to use all the address space, then create a subnet with prefix 192.168.0.0/16 and you will have 65K IPs available for you.
Let me know if you have any further questions.