Finally I am able to create table in oracle using Command Prompt. Thanks very very much PAVB.
I want to ask just one question before closing this thread.

When I connect in command prompt using username,password & Host String(tnsNames.ora). Its succeed as seen below.

Code:
C:\>sqlplus sonia/mypass@sonia - In this line First sonia is the userName & second Sonia is the host from the tnsnames.ora

SQL*Plus: Release 11.2.0.2.0 Production on Wed Jul 4 13:12:43 2012

Copyright (c) 1982, 2010, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Express Edition Release 11.2.0.2.0 - Production

But When I use the sqlPlus screen to connect to Oracle -
UserNAme - sonia
Password - mypass
HostString - sonia

I am getting ERROR - ORA-12514 TNSlistener does not currently know of service requested in connect descriptor.
I am not getting why I am not able to LOGIN FROM SQLPLUS SCREEN.

I searched on the net, But still No LUck.My database is also started which I find using the
Code:
 C:>sc query OracleServiceXE

tnsnames.ora (LOCATION - C:\oracle\product\10.2.0\client_1\network\admin\tnsnames.ora
)
# tnsnames.ora Network Configuration File: C:\oracle\product\10.2.0\client_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

SONIA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = sonia)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = SONIA)
)
)
[/code]


tnsNAmes.ora -C:\oraclexe\app\oracle\product\11.2.0\server\network\ADMIN
Code:
XE =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = sonia)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = XE)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

ORACLR_CONNECTION_DATA = 
  (DESCRIPTION = 
    (ADDRESS_LIST = 
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) 
    ) 
    (CONNECT_DATA = 
      (SID = CLRExtProc) 
      (PRESENTATION = RO) 
    ) 
  )
Listener.ora -C:\oraclexe\app\oracle\product\11.2.0\server\network\ADMIN
Code:
XE =
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\11.2.0\server)
      (PROGRAM = extproc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = sonia)(PORT = 1521))
    )
  )

DEFAULT_SERVICE_LISTENER = (XE)

I am still confused in that I have two tnsNames.ora in different locations.Is that OK?