I've skimmed through the forums here and I can't seem to find any topics answering some questions I have about running and maintaining a good Minecraft server.

First off, I don't need help getting the server working; I've already got that covered.

I just need help with things like..
How do I make myself an admin?
How do I make my map flat, so there's no trees or mountains?
How do I activate commands like /cuboid or /line?
How do I create new worlds?
How do I customize the worlds I've created?
Etc.

I'm sorry if this is stupid to post, and I'm sorry if I'm wasting everyone's time by posting this, I just can't seem to get a straight answer from any location I look.

Thanks guys.

- Ghoul