Birds in flight take a LOT of practice to get good at. Start with easy birds (pigeons or sea gulls... they aren't usually spooked by human attention). I don't know what you have in the way of post-processing software, but any of the big name noise reduction PS add-ons (some come in stand alone programs) or selective blurring will get rid of background noise. BTW, bird photography can be very addicting; you have been warned.