Connect to the database. Use the 'connect' command, it can be shortened to 'conn', saving three keystrokes ;)"SQL>" and what now?
SYS and SYSTEM are both "special" database users, SYSTEM has the dba role, the SYS user "owns" the database instance and system (!) catalog. There isn't much that requires a SYS connection, SYSTEM can do most any task. One thing SYSTEM can not do is shut down the database.
connect system ... password: ... Connected. -- or conn system/<password> ... -- or a SYS connect you *must* use sysdba role conn sys as sysdba; ... Password: ... -- password Not Relevant. If connect error check your OS group membership. -- or use "slash" shortcut for OS authentication conn /as sysdba; ... Connected.
The 2 Day DBA guide can answer many questions faster than posting here ;) http://docs.oracle.com/cd/E17781_01/server.112/e18804/toc.htm
conn system ... password: ... Connected. create user <username> identified by <password>; grant resource, create session, create view to <username>; conn <username> ... password ... Connected.
The actual error would be quite helpful. Sometimes the shortcut URL does not get set up correctly, try this one:... "Get Started With Oracle Database 11g Express Edition" i get an error.