few questions from a beginner

I have just started playing around oracle7. I have a few questions about SQL Plus.
1. What is the datatype which can act as a counter, or a serial number, which can act as primary key in creating a table? 2. If I want to type the whole query in text editor in simple text file, how I can run that query in SQL Plus?
3. I just wrote simple statement

        'create database tmp;'
   It gives me error ' insufficient priviledgs '    

Is there somebody who can really answer my tiny questions? I really do not know unix much. I want to do this query in SQL Plus for oracle7 on Solaris.

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