Difference between oracle database desktop and server class

I installed Oracle database 11g enterprise edition to my laptop. When I was installing Oracle, at the beginning I selected Desktop Class (not server class) option.

Now I am trying to make remote connection to my Oracle database from another PC but I cannot connect to Oracle and get this error message:

"ORA-12545: Connect failed because target host or object does not exist"

even though all Oracle services have been already started.

May the reason be why I installed Oracle as desktop class instead of server class?

My tnsnames.ora file:

ORACLR_CONNECTION_DATA =  (DESCRIPTION =    (ADDRESS_LIST =      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))    )    (CONNECT_DATA =      (SID = CLRExtProc)      (PRESENTATION = RO)    )  )DERS =  (DESCRIPTION =    (ADDRESS = (PROTOCOL = TCP)(HOST =localhost)(PORT = 1521))    (CONNECT_DATA =      (SERVER = DEDICATED)      (SERVICE_NAME = Ders)    )  )