How Do You Get Airplay At Radio Stations For Your Bands Music, Who Must You Contact?

I suggest you start with the local one, Look for a guy who may be interested in local content, and stories, so get a story together about your band. Do not think they  will call you in there, and you can come over like the Rolling Stones, and give the odd grunt and enigmatic raised eyebrow.
If you are unknown, and I am assuming you are, you have to self promote like crazy, you have to be more interesting than the other bands starting out.
So write a script and practice it, send free copies of your C.D. to the radio station. Phone them up and ask who compiles the play list on the show you want to be on, and offer to give away free C.D.s, many do not do this, but you are advertising remember.
Always be on time, and you will be asked back and played, start on the smaller shows and you will get a chance to climb.