How to i ban players on my minecraft server?

I have a server that i bought from gameservers.com and it came with McMyAdmin 2 and every once in a while a very bad person that hacked my server IP joins and does the best in his / her ability to destroy our stuff (we play on survival). I might be a major noob for this but i don't know how to ban players on it. What i really need to know is how do i make my Minecraft account an admin so can type in the commands to ban people. This will Really help with getting this guy to go away.