Memory usage checking of MSSQSL server

Check the total host memory and the used memory using "Task Manager" -> "Performance" (tab)

To check how much memrory is used by MSSQL server instance, the following SQL can be used:
SELECT (physical_memory_in_use_kb/1024) AS Used_Memory_By_SqlServer_MB FROM sys.dm_os_process_memory;

To check the "Max Server Memory" and "Minimum Server Memory":
   In the MSSQL Server Managemenr Studio -> select the instance (Top Parent Node of all) -> right click -> Properties -> Memory.