Hi,
  I want to run all of the following queries at a time:
   1.tablespace creation
   2.user creation
   3.tables creation
   4.insertion of records into the tables
 how I can execute these jobs at a time?
  thanks in advance.
                              -Amitava Deewan

If you can get the SQL sorted then there are several ways to do this including the Scheduler on your machine (AT in Windows, CRON in Unix) which will do this for you.