Do you have to have the installed Minecraft to host a Creative server?
Step 1: Go to
http://www.minecraft.net/Step 2: Log in
Step 3: Click Multiplayer
Step 4: Click where it says 'If you want to host your own, here's the server software!'
Step 5: Download the package
Step 6: Extract
Step 7: Open the folder and click the minecraft server.bat I think it is
Step 8: After you run it for the first time, it downloads a bunch of other folders so you can rename your server, choose to grow trees, etc. It also gives the URL of your server.
I used to host a Minecraft creative server with 3 friends. It was called The Gang of Three. It was awesome, we had a city with a gold floor and lots of houses.