Basic Administrative SQL commands

Create tablespace

 create tablespace tablespacename
  datafile '/path/to/file/filename.dbf'
  size 10m autoextend on
  next 5m maxsize 1G;

This will create a 20mb datafile that will extend by 5mb until it gets to 1gb max.

Add datafile to tablespace

 alter tablespace tablespacename
  add datafile '/path/to/file/filename.dbf'
  size 10m autoextend on
  next 5m maxsize 1G;

Create a user

 create user username
  identified by password
  default tablespace tablespacename
  temporary tablespace temp
  quota unlimited on tablespacename
  account unlock;