Two novice questions

I have two problems. One, I would like to know how to remove a database. It
would always keep saying this:

PostgreSQL said: ERROR: DROP DATABASE: Database "blazeboard" is being
accessed by other users

I'm sure no one else is accessing it because I'm the only one who knows
that the database exists and ps doesn't show any other users connecting to it.

My second question is that I have created a table with a column, FID.
However, when I SELECT FID FROM table, it will result:

blazeboard=# SELECT FID FROM forum;
ERROR:  Attribute 'fid' not found

Could this be a bug? I'm using v7.03 if it matters. Thanks, and please
reply also to my email if you do reply.