If you have played with the TP of this RP, you should have in mind that after the deployment of the RP, you would have to install a SQL hosting server. This is not done anymore as the TP release did.
As already mentioned at the beginning, you should set up your design for MySQL Server PaaS offerings (the t-shirt sizes keyword).
If you want to add a virtual machine with MySQL Server installed, you would have to deploy a VM from an existing template that might have been synchronized earlier from Azure Marketplace using the Syndication feature.
Another location for the MySQL templates is the quick start template GitHub, which can be found here: https://github.com/Azure/AzureStack-QuickStart-Templates/tree/master/mysql-standalone-server-windows.
After the deployment is successful, we need to add it to Azure Stack as the SQL capacity for PaaS.
Finally, we will need to create the SKU in the Azure admin portal, as follows:
Again, as stated with the Microsoft SQL resource provider, based on my experiences, it is good to wait up to 60 minutes before it is visible in the portal because a new SKU needs some time for internal synchronization too.