Scroll down, this question IS asked a lot...in fact, the most recent was TWO DAYS AGO.
http://www.dakkadakka.com/dakkaforum/posts/list/500960.page
Like the previous poster, I am not saying this to be rude...I am saying this because we have to say it about once a week...
There are literally dozens and dozens of threads like this.
Here is the short answer however:
Get a cheap double action, internal mix gravity feed brush.
If you can't find one of those cheap, a siphon feed will do.
The iwata neo is a good cheap starter brush, and can be found at hobby stores and some craft centers.
Get a compressor, the "airbrush" compressor from harbor freight lasted me a long time - i eventually upgraded to get something with an easier pressure adjustment
Get airbrush paints (vallejo model air, aztek, createx, badger, etc) as while you can thin any paints, its a pain.
Subscribe to and watch:
buypainted on youtube
awesomepaintjob.com
best of luck and enjoy the hobby - try to do a bit more research, and then come back with more questions!
enjoy!