Followed below two guidelines

http://www.oracle-base.com/articles/12c/upgrading-to-12c.php

http://allthingsoracle.com/upgrade-to-oracle-database-12c-single-instance/

1. Install oracle12c binaries on existing 11g DB
2. Use Manual Method to upgrade DB
3. below are the reults.

SQL> SELECT CDB FROM V$DATABASE;

CDB
---
NO

SQL> COLUMN NAME FORMAT A8
SQL> SELECT NAME, CON_ID, DBID, CON_UID, GUID FROM V$CONTAINERS ORDER BY CON_ID;

NAME         CON_ID       DBID    CON_UID GUID
-------- ---------- ---------- ---------- --------------------------------
ecdb              0 2690860943          0 0357A41433776FF0E0538B06A8C088FF

But my problem is that there is no CDB or PDB as you have seen in above query
what to do next !!!