Port 1521 is the default one.
You can choose another port number like 1522 but since you are novice it is better to leave the default one (1521)
Port number 1521 is busy because you have create a listener before accepting connection on that port. First you can delete that listener using again Net Configuration Assistant utility and then try to add one in 1521 port
You have to delete the listener that use port 1521. You can do this using Net Configuration Assistant utility: Listener Configuration -> Delete
Then you have to add new listener that use port 1521.
Or you can go to the windows service and stop OracleListener. After that port 1521 will be free.
Listener refused the connection with the following error: ORA-12514, TNS:listener does not currently know of service requested in connect descriptor The Connection descriptor used by the client was: (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=Hyperion)))
Pl do not post duplicates -
continue the discussion in your previous posts