The Select Servers to Monitor window of the Add Servers wizard allows you to select one or more of the SQL Server instances you want to monitor using SQL Diagnostic Manager. If the name of the SQL Server instance you want to monitor does not appear in the list, type the instance name in the space provided in the Available Servers area. You can also designate specific ports for your SQL Server instances by entering a comma between the instance name and port number, for example, domain\instance name, port.
The Available Licenses field shows you the number of instances your current license permits SQL Diagnostic Manager to monitor.
The Select Servers to Monitor window lists all the SQL Server instances provided by your domain controller. This list can include unsupported SQL Server instances. Be sure to select only SQL Server instances that are supported by SQL Diagnostic Manager.
Access the Add Servers wizard
You can open the Add Servers wizard from the SQL Diagnostic Manager Console menu by selecting 
> Manage Servers and clicking Add in the Manage Servers window.