question from a new dba

I would like to ask some questions:

1. How could I know what databases are existing in Oracle ?
2. What is the use of the file "init.ora" under $ORACLEHOME/dbs ?
3. I have tried to create database named "alanddd" by: SQLDBA> startup nomount pfile=init.ora ORACLE instance started. SQLDBA> connect internal Connected. SQLDBA> create database alanddd 2> controlfile reuse 3> ; Statement processed.

   What should I do after these ?? I read the Adminstrator's Guide.    It tells me to startup and shutdown the database system. But I    found that I have to "disconnect" before I shut it down. And    after this, when I tried to startup the database system, it gave    the following error messages:

        SQLDBA> startup
        ORACLE instance started.
        ORA-01103: database name 'ALANDDD' in control file is not 'ORACLE'
        Attempting to shutdown instance........ORACLE instance shut down.

   Now, I could only startup the database system by:
        SQLDBA> startup nomount pfile=init.ora

   What should I do to make the database system works fine as before ??

4. I even now couldn't login sqlplus by:

        dbsvr2%~/dbs > sqlplus
        SQL*Plus: Version 3.0.9.1.2 - Production on Sat Nov 26 23:32:31 1994
        Copyright (c) Oracle Corporation 1979, 1989.  All rights reserved.
        Enter user-name: alan
        Enter password: 
        ERROR: ORA-01033: ORACLE initialization or shutdown in progress

   What should I do ??

5. Where can I get any documentation about Oracle (like FAQ)

   through internet ??

I'm now using Oracle version 6 on a Sparc20 machine. Many many many thanks for help.

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