Moving over from official server
From Mineserver Wiki
If you have already a working Minecraft server, but want to use Mineserver, you can easily move over!
First of all, make a backup of your whole Minecraft server. If anything went differently from your expectations, this will allow you to go back. Second, make sure your Minecraft world is in "old" Beta 1.2 File format. As of 26 Feb. 2011, Mineserver does not support the new Beta 1.3 File format. Beta 1.3 clients can connect though.
Do the work
Install Mineserver in a directory on your server. Edit the settings file to fit your needs, copy your world to the desired path and make sure the path is correctly specified in the settings. That's it! You can start Mineserver and start playing.